From karsten@phy.hw.ac.uk  Mon Jul  5 08:52:01 1999
From: karsten@phy.hw.ac.uk (Karsten Ballueder)
Date: Mon, 05 Jul 99 07:52:01 GMT
Subject: Mahogany 0.23a
Message-ID: <mt2.0-27540-931161121@news.informatik.uni-bonn.de>

A new release of Mahogany has been made.

Binaries for Debian Linux i386, Debian Linux AXP, Sun
Solaris, Windows NT/98/95 and source are available
immediately, binaries for RedHat Linux 5.2 and 6.0 will
follow within the next two days. 

Announcing Mahogany Version 0.23a 
===================================================================== 

Mahogany is an OpenSource(TM) cross-platform mail and news client. It
is available for X11/Unix and MS Windows platforms, supporting a wide
range of protocols and standards, including POP3, IMAP and full MIME
support. Thanks to its built-in Python interpreter it can be extended
far beyond its original functionality.

Mahogany's wealth of features and ease of use make it one of the most
powerful clients available, providing a consistent and intuitive
interface across all supported platforms.

It aims at supporting GNOME (and KDE for that matter) and includes an
extendable address book system supporting hierarchical organisation of
entries, group aliases, searching the database and easy editing, with
support for other program`s address database formats. Currently
Mahogany`s native format and (X)Emacs` BBDB address books are
supported.

Mahogany is being developed using the free wxWindows application
framework, building on the GTK+ toolkit on Unix.

Mahogany is constantly being tested on Linux-x86, Linux-alpha,
Solaris-sparc and MS Windows. It should compile and work on any major
Unix platform.

CHANGES AGAINST RELEASE 0.22a / UPDATE :
===================================================================== 

For the Unix versions, there are few differences, minor bug fixes and
improvements, especially in the message editor, which behaves almost
perfectly now. The major new addition is the Windows version, built
from the same source as the Unix one. We hope to keep both platforms
in sync for the future, making common releases. Also, work on a MacOS
port has left the early stages and is making progress.

- First useable, public Windows release for Windows NT/95/98.
- All known (crash-inducing) bugs fixed.
- Significant message editor/viewer improvements.
- Several minor usability fixes and some significant speed-ups.

DOWNLOAD 
===================================================================== 

        http://mahogany.home.dhs.org/                  
        http://www.phy.hw.ac.uk/~karsten/Mahogany/

        ftp://ronnie.phy.hw.ac.uk/pub/Mahogany/   (UK, Europe)
        ftp://ftp.gdev.net/pub/Mahogany/          (US)

NEXT 
===================================================================== 

For the next release we are currently working on the following:

     completion of filtering rules/scoring code     
     asynchoronous folder access and multi-threading
     subscription management for NNTP/IMAP/newsspool 
     Templates/style-sheets for message composition and flexible reply handling 
     DND with KDE/Gnome filemanagers (now supported by wxGTK) 
     Messages sorting, threading, scoring and searching 
 possibly also:
     GPG/PGP support 
     built-in HTML viewer
     Finish the new message editor code: rich-text editing 

== 
 Karsten Ballüder  http://Ballueder.home.dhs.org/  mailto:karste-@phy.hw.ac.uk
 Physics Department, Heriot-Watt University, Edinburgh, EH14 4AS, Scotland
                     Tel. +44-(0)-131-4513068  Fax. +44-(0)-131-4513136
            "In a world without fences, who needs Gates?"

<P><A HREF="http://mahogany.home.dhs.org/">Mahogany 0.23a</A> -
open-source graphical mail/news client for Unix and MS Windows,
using the wxWindows toolkit.  (29-Jun-99)

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From irmen@bigfoot.com  Mon Jul  5 08:52:28 1999
From: irmen@bigfoot.com (Irmen de Jong)
Date: Mon, 05 Jul 99 07:52:28 GMT
Subject: AmigaPython 1.5.2
Message-ID: <mt2.0-27540-931161148@news.informatik.uni-bonn.de>

ANNOUNCING:

                AmigaPython 1.5.2 - build 1

                The Amiga version of Python.
           
           by Irmen de Jong - irmen@bigfoot.com

WHAT IT IS:

This is the Python interpreter (version 1.5.2) for AmigaDOS.
It is provided as an easy to install package.

WHAT'S NEW ?

Obviously, this version is based on the 1.5.2 source code and libraries.
So you'll benefit from all the great new things 1.5.2 has to offer over
the previous version (1.5.1).

WHERE CAN I GET IT ?

>From Aminet <http://www.aminet.org/~aminet/>, in the dev/lang directory:

Python152.lha      dev/lang   1.0M   1 Python language 1.5.2 (bin+lib)
Python152_Doc.lha  dev/lang   897K   1 Python 1.5.2 documentation (HTML)
Python152_Src.lha  dev/lang   734K   1 Python language 1.5.2 (source)

It comes with a Python-style license, but is otherwise free for
commercial and non-commercial use.

REFERENCE:

<P><A HREF="http://www.bigfoot.com/~irmen/python.html">AmigaPython
1.5.2</A> - AmigaDOS port of Python 1.5.2.  (29-Jun-99)

== 
Irmen de Jong - irmen@bigfoot.com

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From akuchlin@mems-exchange.org  Mon Jul  5 08:53:21 1999
From: akuchlin@mems-exchange.org (Andrew M. Kuchling)
Date: Mon, 05 Jul 99 07:53:21 GMT
Subject: Remote Microscope 1.0a3 released
Message-ID: <mt2.0-27540-931161201@news.informatik.uni-bonn.de>

The latest release of the remote microscope software, version
1.0alpha3, is now available in source code form.  The code has been
running on CNRI's demo microscope for a few weeks, and I've been
pleased with the results; the server seems to be much more reliable
than 1.0a2, and people have liked the new Z-axis control.

The only significant new feature in this release is that you can now
control the Z-axis from the client, in order to manually focus an
image when the autofocus produces a blurry result.  There's also a
host of minor fixes and improvements; most notably, various bugs were
found that made the server hang indefinitely.  These bugs have been
fixed, and consequently the 1.0alpha3 server is a lot more stable than
1.0a2.

Remote microscope home page:
       http://www.mems-exchange.org/exchange/software/microscope/
List of changes:
       http://www.mems-exchange.org/exchange/software/files/microscope/CHANGES

== 
A.M. Kuchling			http://starship.python.net/crew/amk/
Men of action, I notice, are rarely humble, even in situations where action of
any kind is a great mistake, and masterly inaction is called for.
    -- Robertson Davies, _The Table Talk of Samuel Marchbanks_

<P><A HREF="http://www.mems-exchange.org/software/microscope/">Remote
Microscope 1.0a3</A> - CNRI Remote Optical Microscope Software.  (29-Jun-99)

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From Amos@digicool.com  Mon Jul  5 08:54:19 1999
From: Amos@digicool.com (Amos Latteier)
Date: Mon, 05 Jul 99 07:54:19 GMT
Subject: Zope Weekly News - Wed, 30 Jun 1999
Message-ID: <mt2.0-27540-931161259@news.informatik.uni-bonn.de>

Hi,

This week saw the release of ZCatalog, the first component of the Zope
Portal Toolkit. Finally searching Zope objects is becoming easier.
Behind the scenes work continues on Zope 2.0. Jim Fulton estimated that
Zope 2 will enter beta in 3 weeks. In addition, Eric Raymond's mention
of Zope this week (at Microsoft and in an essay) is further proof that
Zope is becoming an influential open source project.

  * Jonathan Corbet pointed out that Eric Raymond mentioned Zope in his
latest essay, "The Magic Cauldron". He discusses Zope in the context of
how to make a living with open source. He calls Digital Creation's model
"Give Away the Recipe, Open A Restaurant".
  
  http://www.tuxedo.org/~esr/writings/magic-cauldron/
 
http://www.tuxedo.org/~esr/writings/magic-cauldron/magic-cauldron-9.html
#ss9.3
  
  * Michel Pelletier announced the first release of ZCatalog. This is
the first component of the Zope Portal Toolkit to be released. ZCatalog
allows indexing and searching of Zope objects.
  
  http://www.zope.org/Download/ZCatalog
  http://www.zope.org/pipermail/zope/1999-June/006059.html
  
  * Butch Landingin announced release 0.1.5 of his Squishdot Zope news
and discussion Product.
  
  http://members.tripod.com/squishdot/index.html
  http://www.zope.org/pipermail/zope/1999-June/006077.html

  * Mark Pratt announced that the second Berlin Zope Barbecue went well
and that the next one is planned for July 16.
  
  http://www.zope.org/pipermail/zope/1999-June/006020.html
  
  * FTP/DAV editing issues came up once again this week. Customizing FTP
and DAV behavior is a complex problem. Some creative ideas were
discussed, but no definitive solution has emerged yet.
  
  http://www.zope.org/pipermail/zope/1999-June/006115.html
  http://www.zope.org/pipermail/zope/1999-June/006171.html
  
  * Phillip Eby and others worked on a solution to displaying data from
a SQL database as a dynamic tree. Cool!
  
  http://www.zope.org/pipermail/zope/1999-June/006087.html
  
  * @mgmt announced that they will offer Zope hosting services.
  
  http://www.mgmt-inc.com/
  
  * Pam Crosby announced some Zope Documentation plans.
  
  http://www.zope.org/pipermail/zope/1999-June/006177.html
  
  * Thilo Mezger announced a mailing list for the Zope
Internationalization Project.
  
  http://www.eevolute.com/mailman/listinfo/zip
  http://www.zope.org/pipermail/zope-dev/1999-June/000651.html
  
Keep on Zoping.

-Amos

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

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From Jeff Rush" <jrush@summit-research.com  Mon Jul  5 08:54:46 1999
From: Jeff Rush" <jrush@summit-research.com (Jeff Rush)
Date: Mon, 05 Jul 99 07:54:46 GMT
Subject: Python 1.5.2 and Fnorb 1.01 for OS/2 Now Available
Message-ID: <mt2.0-27540-931161286@news.informatik.uni-bonn.de>

Python 1.5.2 and Fnorb 1.01 for OS/2

My port of Python and Fnorb to OS/2 has been updated to the latest
stable versions.  Besides the improvements of 1.5.2, a threading
module bug was fixed that prevented Fnorb from multithreading
CORBA requests, posix.chdir() was enhanced to support changing
the current drive and a bug was fixed in time.sleep().

    http://warped.cswnet.com/~jrush/python_os2/

<P><A HREF="http://warped.cswnet.com/%7Ejrush/python_os2/">OS/2 Release</A>
- of Python 1.5.2 and Fnorb 1.01.  (30-Jun-99)

Jeff Rush <jrush@summit-research.com>

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From planders@mail.utexas.edu  Mon Jul  5 08:56:24 1999
From: planders@mail.utexas.edu (Preston Landers)
Date: Mon, 05 Jul 99 07:56:24 GMT
Subject: Pagecast 1.0: submit lists of URLs to search engine spiders
Message-ID: <mt2.0-27540-931161384@news.informatik.uni-bonn.de>

Announcing the first release of Pagecast, a tool written in Python to
aid in submitting (potentially large) lists of URL's to search engine
spiders such as AltaVista, Hotbot, Excite, etc.  

See http://askpreston.com/projects/pagecast/index.html

for more information.

Pagecast is distributed under the GNU General Public License.  

Summary -- 
 
 Pagecast can run from either the command line or as a mail robot.  It
 is easily configured via .conf files.  The basic action is to take a
 line-separated list of URL's from a file, standard input, or the body
 of a mail message and submit these URL's in a multithreaded fashion
 to a variety of Internet search engines.  Essentially, it automates
 the "suggest a site" procedure offered by most search engines.

 Pagecast 1.0 comes pre-configured with 6 popular search engines
 (Excite, Hotbot, Infoseek, AltaVista, Google, and Lycos.)  It is
 relatively easy to add additional search engines without delving into
 the actual Python code.

 There are some 'advanced' features such as the ability to download
 and scan the URLs for outdated date meta tags or low keyword-to-title
 relevence.  These features could use some refinement.

This software is distributed under the GPL.  I hope someone finds it
useful and perhaps contributes to its further development.  I will
make bug-fix releases as neccesary, however, I am not actively working
on it at the moment having more exciting Python projects in the works.

At any rate, I would love to hear anybody's comments.  

Sincerely,

Preston Landers
planders@mail.utexas.edu


<P><A HREF="http://askpreston.com/projects/pagecast/index.html">Pagecast
1.0</A> - submit lists of URLs to search engine spiders.  (02-Jul-99)

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From mwh21@cam.ac.uk  Mon Jul  5 09:00:05 1999
From: mwh21@cam.ac.uk (Michael Hudson)
Date: Mon, 05 Jul 99 08:00:05 GMT
Subject: bytecodehacks 0.50
Message-ID: <mt2.0-27540-931161605@news.informatik.uni-bonn.de>

[Moderator's note: "Abstract: This package contains a library of routines
for editing the bytecodes executed by the Python virtual machine, and a set
of routines that use the library to do unlikely things to Python functions
and methods, such as locally binding references and inlining functions."]

It's been a while, but there's a new version of bytecodehacks on the
starship:

http://starship.python.net/crew/mwh/

Quite a lot has changed, especially under the hood. There's a
design-by-contract module, a function that will make another tail
recursive, a set of simple rationalizations/optimizations (originally
posted comp.lang.python by Corran Webster) and probably lots of stuff I've
forgotten about.

The documentation has been updated, but there are probably places
where it's out of date, or just plain wrong. If you find such a place
please do tell me!

The documentation contains what I think is quite a nice description of
one way of avoiding cycles in complex data structures (look at the
doumentation of fleshy).

Have fun, and thanks for reading!

Michael

<P><A HREF="http://starship.python.net/crew/mwh/">bytecodehacks 0.50</A> -
use manipulations of virtual machine bytecodes to do unlikely things in
Python!  (04-Jun-99)

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From krp02078@my-deja.com  Wed Jul  7 02:16:39 1999
From: krp02078@my-deja.com (krp02078@my-deja.com)
Date: Wed, 07 Jul 99 01:16:39 GMT
Subject: DIALOG.py
Message-ID: <mt2.0-1723-931310199@news.informatik.uni-bonn.de>

Hi everybody!

[Moderator's note: "Dialog is a program that will let you to present a
variety of questions or display messages using dialog boxes from a shell
script. Currently, these types of dialog boxes are implemented: yes/no box,
menu box, input box, message box, text box, info box, checklist box,
radiolist box, and gauge box." (from the Linux man page for "dialog")]

Just finished this module, and thought it could be useful:
DIALOG.py - an interface to the famous dialog program
get it from http://www.brigadoon.de/peter/DIALOG.py

ciao,

	pete

== 
-rw-r--r--   1 kruse    users          66 Nov  2 11:50 .signature

<P><A HREF="http://www.brigadoon.de/peter/DIALOG.py">DIALOG.py</A> - interface
to the &quot;dialog&quot; program for text-based dialog boxes.  (30-Jun-99)

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From fleck@informatik.uni-bonn.de  Wed Jul  7 02:18:34 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Wed, 07 Jul 99 01:18:34 GMT
Subject: [fm] pyWeather 0.1b
Message-ID: <mt2.0-1723-931310313@news.informatik.uni-bonn.de>

  pyWeather 0.1b
  groundhog - June 30th 1999, 12:53 EST

  pyWeather is a small python script that retreaves the local weather
  conditions from weather.noaa.gov and then mails the results to any
  given email over an SMTP server. It's beta but it works.

  Changes: Initial Release - Fixed a small bug with temp file creation in
  the earlier version.

    Download: http://members.bellatlantic.net/~rasclkng/pyWeather.tar.gz
    Homepage: http://members.bellatlantic.net/~rasclkng/

                  Author: Groundhog
                 License: GPL
                Category: Console/eMail

  Freshmeat copyright © 1999 scoop@freshmeat.net

<P><A HREF="http://members.bellatlantic.net/~rasclkng/">pyWeather 0.1b</A> -
retrieve local weather conditions from weather.noaa.gov and forward them
via email/SMTP.  (30-Jun-99)

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From fleck@informatik.uni-bonn.de  Wed Jul  7 02:20:30 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Wed, 07 Jul 99 01:20:30 GMT
Subject: [fm] wxPython 2.1b1
Message-ID: <mt2.0-1723-931310430@news.informatik.uni-bonn.de>

  wxPython 2.1b1
  rogue - June 28th 1999, 20:49 EST

  wxPython is an extension module for Python that wraps the wxWindows
  cross platform GUI library, and is quickly becoming a very popular
  alternative to Tkinter and PythonWin. This extension module attempts to
  mirror the class hierarchy of wxWindows as closely as possible and is
  very versatile. It can be used to create standalone GUI applications,
  or can be used in in situations where Python is embedded in a wxWindows
  C++ application as an internal scripting or macro language. Currently
  supported GUIs are Win32 and GTK/X-Windows.

  Changes: Added the Printing Framework, Sizers, and a boatload of minor
  tweaks and fixes.

      Download:http://alldunn.com/wxPython/main.html#download
      Homepage:http://alldunn.com/wxPython/

                  Author: Robin Dunn
                 License: OpenSource
                Category: Development/Python Modules

  Freshmeat copyright © 1999 scoop@freshmeat.net

<P><A HREF="http://alldunn.com/wxPython/">wxPython 2.1b1</A> - interface
to the wxWindows v2 free cross-platform GUI library; now includes
printing framework.  (28-Jun-99)

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From arcege@shore.net  Wed Jul  7 02:22:22 1999
From: arcege@shore.net (Michael P. Reilly)
Date: Wed, 07 Jul 99 01:22:22 GMT
Subject: ExpectPy 1.8.2 - Expect extension for Python
Message-ID: <mt2.0-1723-931310542@news.informatik.uni-bonn.de>

I've created a patch release for ExpectPy which fixes some Linux
bugs and build problems.

I have also moved the ExpectPy webpage to Starship Python:
  http://starship.python.net/crew/arcege/ExpectPy/
The old URL points to the new location.  The author's email address
is arcege@shore.net.

Note:  Expect does not support Tcl 8.1 (and is expected to support
Tcl 8.2 instead); the regular expression engine and interface in
Tcl 8.1 changed making Expect and ExpectPy unusable with that
release.  This may cause problems when compiling ExpectPy with
earlier versions of Tcl, and compiling Tkinter with Tcl/Tk 8.1.

  -Arcege

Changes since 1.8:
* Linux has different mechanisms for extended CBAUD and for when a
  terminal detects EOF (the error EIO is returned).
* Add helper macros to the code for better readability.
* Make the C code more compilable (K&R C).
* Fix various build issues.
* Add a new option to the configure script to force using static
  libraries.
* Beta releases of Python include a "bN" in the version string,
  strip this inside the configure script.
* Handle searching for the pthread library.
* Make some minor changes for using Tcl 8.1 in a later release.
* Change the ask.py example to use the new stty method instead of
  termios (which I find is not compiled on many systems).
* Fix a bug where setattr of the settings object could receive a NULL.

<P><A HREF="http://starship.python.net/crew/arcege/ExpectPy/">ExpectPy
1.8.2</A> - Python adaptation of Don Libes's "Expect" library for automation
of interactive UNIX processes.  (05-Jul-99)

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From Fred L. Drake, Jr." <fdrake@acm.org  Wed Jul  7 02:26:03 1999
From: Fred L. Drake, Jr." <fdrake@acm.org (Fred L. Drake)
Date: Wed, 07 Jul 99 01:26:03 GMT
Subject: Updated Python documentation available!
Message-ID: <mt2.0-1833-931310763@news.informatik.uni-bonn.de>

Updated documentation for Python 1.5.2 is now available.  The online
version is available at:

	http://www.python.org/doc/

  Archives of the documentation in HTML, LaTeX, PDF, and PostScript
formats are available at the same location, and may also be downloaded
via FTP from:

	ftp://ftp.python.org/pub/python/doc/

  If you have any questions or comments on the documentation, please
send email to:

	python-docs@python.org

  Many additional modules have been documented (22 more!).  Many small
improvements have been made to other parts of the documentation as
well.  The following modules are now documented:

  asyncore	    dl                sched           
  chunk		    fpformat          SimpleHTTPServer
  cmp		    htmlentitydefs    statcache       
  cmpcache	    mutex             statvfs         
  codeop	    new               sunau           
  curses	    nis               SUNAUDIODEV     
  dircache	    pty               tty
  dl		    rlcompleter   

  Windows users:  If you installed Python using the installer rather
than by building from source, you can get the updated documentation by 
downloading the HTML archive and unpacking it into the "Doc" directory 
of your installation.

  Most of the new sections were contributions from the Python
community; your help makes the Python documentation some of the best
available for any free programming language!

  Enjoy!


  -Fred

== 
Fred L. Drake, Jr.	     <fdrake@acm.org>
Corporation for National Research Initiatives

<P><A HREF="http://www.python.org/doc/">Updated Python 1.5.2
documentation</A> - with 22 additional modules documented and
many small improvements.  (06-Jul-99)

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From simone@oreilly.com  Wed Jul  7 23:56:06 1999
From: simone@oreilly.com (simone@oreilly.com)
Date: Wed, 07 Jul 99 22:56:06 GMT
Subject: REGISTRATION REMINDER FOR OPEN SOURCE CONVENTION
Message-ID: <mt2.0-6317-931388166@news.informatik.uni-bonn.de>

If you're planning to attend this year's O'Reilly Open Source Software
Convention in Monterey, CA, August 21-24 (covering Perl, Apache,
Linux, sendmail, Tcl/Tk, Python, as well as an Open Source business
track) , you'll probably want to register soon -- discounts of up to
$200, as well as an exclusive Open Source Convention T-shirt, apply
ONLY to registrations before July 15th. 
Hope to see you there!

For more information, or to register, see:
http://conferences.oreilly.com

Simone Paddock
O'Reilly & Associates
101 Morris Street
Sebastopol, CA 95472
simone@oreilly.com

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From neale-news@pobox.com  Thu Jul  8 00:05:39 1999
From: neale-news@pobox.com (Neale Pickett)
Date: Wed, 07 Jul 99 23:05:39 GMT
Subject: New location for whiz, html.py phonebook.pl, and my other goodies
Message-ID: <mt2.0-6398-931388739@news.informatik.uni-bonn.de>

Apparently more people are using my software than I realized :-)

The new location for my stuff (short descriptions follow) is:

  http://starship.python.net/crew/neale/src/

(Which is probably where it should have been in the first place.)

For those keeping track, the major offerings are:

  whiz -- html forms tool for creating "wizards" (anyone want to
          integrate this into bobo?  I hear they're looking for one.)

  html.py -- some classes for generating HTML, in the spirit of HTMLgen, 
             but all in a single file, and it spits out indented code.

  phonebook -- HTTP to LDAP gateway; makes a web server look like RFC
               1959; also provides nice web output and homepage
               redirection.  See http://ldap.lanl.gov/ for a live demo.

  other stuff -- IRC class for writing bots and clients, an interactive
                 choose-your-own-adventure CGI, and some other
                 non-pythonic toys.

Enjoy

Neale Pickett

<P><A HREF="http://starship.python.net/crew/neale/src/">Misc. HTML tools
(new location)</A> - whiz, for creating HTML &quot;wizards&quot;; html.py,
for generating HTML; phonebook, a HTTP to LDAP gateway; IRC bot
classes; etc.  (07-Jul-99)

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From jcw@equi4.com  Thu Jul  8 00:18:17 1999
From: jcw@equi4.com (Jean-Claude Wippler)
Date: Wed, 07 Jul 99 23:18:17 GMT
Subject: Minotaur 0.1 - bridging Tcl, Python, and Perl
Message-ID: <mt2.0-6596-931389497@news.informatik.uni-bonn.de>

This is the first public announcement of a generalized extension which
lets you run Python scripts from Tcl, or Tcl from Perl, or any of the
other combinations.

Minotaur works by loading the appropriate shared library into another
script language's context.  So, for example, running Tcl from Python
means that the Python main program imports the Minotaur extension, which
in turn loads the Tcl libraries - thus Tcl becomes "embedded" into the
Python runtime environment (which is similar to embedding Tcl in a
normal C program).  As involved as that sounds, performance is already
surprisingly good, and the capability is turning out to be quite useful.

Minotaur 0.1 is an alpha level release, meaning: it works, aside from a
few quirks (see below), and bugs, but its API and implementation might
still change in incompatible ways in future releases.

An example, embedding a Tcl script in Python:
        import Minotaur
        Minotaur.initTcl()
        print Minotaur.Tcl("expr {1111 + 2222}")
        Minotaur.Tcl("""
            set result "Tcl version [info patchlevel]"
            Python "result = '$result'"
        """)
        print result

As you can see, a value is returned either directly (only if it's an
integer), or by using a reverse embedding, i.e. executing a Python
statement from the embedded Tcl system.  Also, this shows how tricky
quoting could get once you start mixing languages in this manner.  And
last but not least, note that the different language contexts are
separate: the two "result" variables used above are not related in any
way (one for Tcl, one for Python).  Also, Minotaur does not yet let you
share data, it merely lets you evaluate scripts (and copy things).

Now the gotcha's, quite a list of them right now:

- You need shared libraries to use Minotaur. Standard installations,
  especially of Perl and Python, do not always include these.  The
  Minotaur homepage has some info on rebuilds you might need to do.
- Tcl/Python can call Perl but to get results back, I had to introduce
  a secondary shared library, dynamically bound to the Perl runtime.
- There is currently no other interface than evaluating a single string.
  Passing int/string/whatever args efficiently is planned for later.
- The Minotaur extension has only been tested for Linux and Windows, but
  is built in a way which should also work on the Mac, and on all Unix
  systems, even those which do not support back-linking in shared libs. 
- Minotaur uses some global data; it's not yet re-entrant / thread-safe.
  As a matter of fact, Minotaur is still totally ignorant of threads.
- I have not yet succeeded in getting Minotaur working on the Mac, and
  ran into problems when trying to launch Tk from Python (Win/Linux).
- The current release does not include any Minotaur binaries, you may
  have to do quite a bit of tweaking to get this stuff to work for you.
  One of my plans is to substantially simplify deployment of all this.

And here's the fun part of things:

 - Minotaur uses Forth as low-level "super-glue" language.  This offers
   the ability to deal with all the inevitable "impedance mismatches"
   which will occur when crossing widely different software designs.
   Also, this can be done without compilation (and often portably).
 - Timing tests indicate that the overhead of calling through Minotaur
   is very low, when the necessary symbol lookups are done in advance.
   The C-based Forth in here uses pForth, and includes quite a bit of
   standard ("ANS") Forth for now, though this may change in the future.
 - The Minotaur extension is loadable from Perl, Python, and Tcl, 'cause
   it exports initialization calls for each of them.  This is essential,
   since the embedded language needs to reopen the extension to gain
   access to the same Forth context as the one which loaded it (this is
   how each embedded language can call back into its parent context).
 - Forth primitives have been defined which can open, lookup, and locate
   routines exported from shared libraries.  Due to the flexibility and
   performance of Forth, everything else needed to embed one language in
   the other is done in Forth, i.e. at run time.  Forth has no idea that
   it is being used to tie scripting languages together, for example.
 - Minotaur, and these shared library access functions have been tested
   on Linux, Windows, and Mac (partially).  The Forth code needed to
   implement such language bindings differs only in pathnames, so far.
 - But this is only the tip of the iceberg, really.  Proof-of-concept
   bindings have also been created for Java, MS COM, Lua, ICI, and PHP.

Minotaur is a spinoff of my long-term "TinyScript" project and is open
source, with a BSD-style license (do whatever you like with it, just
leave the copyright attributions intact, and don't sue me).  Minotaur
was written to see how far one could go in bringing scripting worlds
together, and to help me tie my own extensions into a range of languages
without having to write a whole range of interfaces.  It hasn't met this
goal yet, but my hope is that it will be of use to others and that a
number of language experts will extend and improve the mechanism so it
works well with all of them.

Minotaur has sort of a homepage here:
        http://mini.net/pub/ts2/minotaur.html
A mirror copy of my working area is being tracked here:
        http://mini.net/pub/ts2/  (a.k.a. ftp://mini.net/pub/ts2/)
And a snapshots of the whole area was recently created as:
        http://mini.net/pub/ts2-19990704.tar.gz

There is no documentation, release 0.1 is a "use the source Luke" kind
of project, but if you would like to try this out - or better still:
participate in whatever way you like - feel free to subscribe to the
Minotaur mailing list, by sending an email to minotaur-add@mini.net. 
There are a handful of subscribers now, with just a few outbursts of
discussions of where to take this, so far.  Which, at this stage, is
still a very open-ended question, IMO.

Comments, suggestions, praise, but especially offering to help with
whetever aspect of Minotaur you'd like to improve are most welcome. 
Language and platform bashing - yawn - will be redirected to /dev/null. 
If you wish to help lower language barriers, so that more code can be
re-used, more interfacing problems can be solved, and perhaps one day
even generic extensions can be written which serve multiple contexts,
please have a look at Minotaur and consider helping to make it happen.

One interesting option, would be to create a binding in SWIG which
generates the low-level glue to Forth, as well as language-specific
wrappers.  The key advantage is that this could let SWIG be used
entirely as a run-time tool, with no compiler/compilation in sight
(assuming the target library exists in shared library form, that is).

-- Jean-Claude Wippler <jcw@equi4.com>

P.S.  This announcement was posted to a range of newsgroups, but was not
      crossposted to avoid serving as flame bait for YAFLC (Yet Another
      Fruitless Language Comparison).  The list of newsgroups is:
		comp.lang.forth
		comp.lang.misc
		comp.lang.perl.moderated
		comp.lang.python
		comp.lang.tcl
      It's a lotta posting for such an early project, but that's because
      there seems to be no established "intra-lingual" newsgroup for
      this stuff.

<P><A HREF="http://mini.net/pub/ts2/minotaur.html">Minotaur 0.1</A> - 
run Python scripts from Tcl, or Tcl from Perl, or any of the
other combinations.  (06-Jul-99)

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:26:53 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:26:53 GMT
Subject: Python Language FAQ - Table of Contents
Message-ID: <mt2.0-6734-931390013@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Table of Contents

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

1. General information and availability

1.1.  What is Python?
1.2.  Why is it called Python?
1.3.  How do I obtain a copy of the Python source?
1.4.  How do I get documentation on Python?
1.5.  Are there other ftp sites that mirror the Python distribution?
1.6.  Is there a newsgroup or mailing list devoted to Python?
1.7.  Is there a WWW page devoted to Python?
1.8.  Is the Python documentation available on the WWW?
1.9.  Are there any books on Python?
1.10. Are there any published articles about Python that I can
      reference?
1.11. Are there short introductory papers or talks on Python?
1.12. How does the Python version numbering scheme work?
1.13. How do I get a beta test version of Python?
1.14. Are there copyright restrictions on the use of Python?
1.15. Why was Python created in the first place?
1.16. Do I have to like "Monty Python's Flying Circus"?
1.17. What is Python good for?
1.18. Can I use the FAQ Wizard software to maintain my own FAQ?
1.19. Which editor has good support for editing Python source code?

----------------------------------------------------------------------------

2. Python in the real world

2.1.  How many people are using Python?
2.2.  Have any significant projects been done in Python?
2.3.  Are there any commercial projects going on using Python?
2.4.  How stable is Python?
2.5.  What new developments are expected for Python in the future?
2.6.  Is it reasonable to propose incompatible changes to Python?
2.7.  What is the future of Python?
2.8.  What is the PSA, anyway?
2.9.  How do I join the PSA?
2.10. What are the benefits of joining the PSA?
2.11. Is Python Y2K (Year 2000) Compliant?

----------------------------------------------------------------------------

3. Building Python and Other Known Bugs

3.1.  Is there a test set?
3.2.  When running the test set, I get complaints about floating point
      operations, but when playing with floating point operations I cannot
      find anything wrong with them.
3.3.  Link errors after rerunning the configure script.
3.4.  The python interpreter complains about options passed to a script
      (after the script name).
3.5.  When building on the SGI, make tries to run python to create
      glmodule.c, but python hasn't been built or installed yet.
3.6.  I use VPATH but some targets are built in the source directory.
3.7.  Trouble building or linking with the GNU readline library.
3.8.  Trouble with socket I/O on older Linux 1.x versions.
3.9.  Trouble with prototypes on Ultrix.
3.10. Other trouble building Python on platform X.
3.11. How to configure dynamic loading on Linux.
3.12. I can't get shared modules to work on Linux 2.0 (Slackware96)?
3.13. Trouble when making modules shared on Linux.
3.14. How to use threads on Linux.
3.15. Errors when linking with a shared library containing C++ code.
3.16. I built with tkintermodule.c enabled but get 'Tkinter not found'
3.17. I built with Tk 4.0 but Tkinter complains about the Tk version.
3.18. Compilation or link errors for the _tkinter module
3.19. I configured and built Python for Tcl/Tk but "import Tkinter"
      fails.
3.20. Tk doesn't work right on DEC Alpha.
3.21. Several common system calls are missing from the posix module.
3.22. ImportError: No module named string, on MS Windows.
3.23. Core dump on SGI when using the gl module.
3.24. "Initializer not a constant" while building DLL on MS-Windows
3.25. Output directed to a pipe or file disappears on Linux.
3.26. Syntax Errors all over the place in Linux with libc 5.4
3.27. Crash in XIO on Linux when using Tkinter.
3.28. How can I test if Tkinter is working?
3.29. Is there a way to get the interactive mode of the python
      interpreter to perform function/variable name completion?
3.30. Why is the Python interpreter not built as a shared library?
3.31. Build with GCC on Solaris 2.6 (SunOS 5.6) fails
3.32. Running "make clean" seems to leave problematic files that cause
      subsequent builds to fail.

----------------------------------------------------------------------------

4. Programming in Python

4.1.  Is there a source code level debugger with breakpoints, step,
      etc.?
4.2.  Can I create an object class with some methods implemented in C
      and others in Python (e.g. through inheritance)? (Also phrased as: Can
      I use a built-in type as base class?)
4.3.  Is there a curses/termcap package for Python?
4.4.  Is there an equivalent to C's onexit() in Python?
4.5.  When I define a function nested inside another function, the
      nested function seemingly can't access the local variables of the outer
      function. What is going on? How do I pass local data to a nested
      function?
4.6.  How do I iterate over a sequence in reverse order?
4.7.  My program is too slow. How do I speed it up?
4.8.  When I have imported a module, then edit it, and import it again
      (into the same Python process), the changes don't seem to take place.
      What is going on?
4.9.  How do I find the current module name?
4.10. I have a module in which I want to execute some extra code when
      it is run as a script. How do I find out whether I am running as a
      script?
4.11. I try to run a program from the Demo directory but it fails with
      ImportError: No module named ...; what gives?
4.12. I have successfully built Python with STDWIN but it can't find
      some modules (e.g. stdwinevents).
4.13. What GUI toolkits exist for Python?
4.14. Are there any interfaces to database packages in Python?
4.15. Is it possible to write obfuscated one-liners in Python?
4.16. Is there an equivalent of C's "?:" ternary operator?
4.17. My class defines __del__ but it is not called when I delete the
      object.
4.18. How do I change the shell environment for programs called using
      os.popen() or os.system()? Changing os.environ doesn't work.
4.19. What is a class?
4.20. What is a method?
4.21. What is self?
4.22. What is an unbound method?
4.23. How do I call a method defined in a base class from a derived
      class that overrides it?
4.24. How do I call a method from a base class without using the name
      of the base class?
4.25. How can I organize my code to make it easier to change the base
      class?
4.26. How can I find the methods or attributes of an object?
4.27. I can't seem to use os.read() on a pipe created with os.popen().
4.28. How can I create a stand-alone binary from a Python script?
4.29. What WWW tools are there for Python?
4.30. How do I run a subprocess with pipes connected to both input and
      output?
4.31. How do I call a function if I have the arguments in a tuple?
4.32. How do I enable font-lock-mode for Python in Emacs?
4.33. Is there a scanf() or sscanf() equivalent?
4.34. Can I have Tk events handled while waiting for I/O?
4.35. How do I write a function with output parameters (call by
      reference)?
4.36. Please explain the rules for local and global variables in
      Python.
4.37. How can I have modules that mutually import each other?
4.38. How do I copy an object in Python?
4.39. How to implement persistent objects in Python? (Persistent ==
      automatically saved to and restored from disk.)
4.40. I try to use __spam and I get an error about
      _SomeClassName__spam.
4.41. How do I delete a file? And other file questions.
4.42. How to modify urllib or httplib to support HTTP/1.1?
4.43. Unexplicable syntax errors in compile() or exec.
4.44. How do I convert a string to a number?
4.45. How do I convert a number to a string?
4.46. How do I copy a file?
4.47. How do I check if an object is an instance of a given class or of
      a subclass of it?
4.48. What is delegation?
4.49. How do I test a Python program or component.
4.50. My multidimensional list (array) is broken! What gives?
4.51. I want to do a complicated sort: can you do a Schwartzian
      Transform in Python?
4.52. How to convert between tuples and lists?
4.53. Files retrieved with urllib contain leading garbage that looks
      like email headers.
4.54. How do I get a list of all instances of a given class?
4.55. A regular expression fails with regex.error: match failure.
4.56. I can't get signal handlers to work.
4.57. I can't use a global variable in a function? Help!
4.58. What's a negative index? Why doesn't list.insert() use them?
4.59. How can I sort one list by values from another list?
4.60. Why doesn't dir() work on builtin types like files and lists?
4.61. How can I mimic CGI form submission (METHOD=POST)?
4.62. If my program crashes with a bsddb (or anydbm) database open, it
      gets corrupted. How come?
4.63. How do I make a Python script executable on Unix?
4.64. How do you remove duplicates from a list?
4.65. Are there any known year 2000 problems in Python?
4.66. I want a version of map that applies a method to a sequence of
      objects! Help!
4.67. How do I generate random numbers in Python?
4.68. How do I access the serial (RS232) port?
4.69. Images on Tk-Buttons don't work in Py15?
4.70. Where is the math.py (socket.py, regex.py, etc.) source file?
4.71. How do I send mail from a Python script?
4.72. How do I avoid blocking in connect() of a socket?
4.73. How do I specify hexadecimal and octal integers?
4.74. How to get a single keypress at a time?
4.75. How can I overload constructors (or methods) in Python?
4.76. How do I pass keyword arguments from one method to another?
4.77. What module should I use to help with generating HTML?
4.78. How do I create documentation from doc strings?
4.79. How do I read (or write) binary data?
4.80. I can't get key bindings to work in Tkinter
4.81. "import crypt" fails
4.82. Are there coding standards or a style guide for Python programs?
4.83. How do I freeze Tkinter applications?
4.84. How do I create static class data and static class methods?
4.85. __import__('x.y.z') returns <module 'x'>; how do I get z?
4.86. Basic thread wisdom
4.87. Why doesn't closing sys.stdout (stdin, stderr) really close it?
4.88. What kinds of global value mutation are thread-safe?
4.89. How do I modify a string in place?
4.90. How to pass on keyword/optional parameters/arguments

----------------------------------------------------------------------------

5. Extending Python

5.1.  Can I create my own functions in C?
5.2.  Can I create my own functions in C++?
5.3.  How can I execute arbitrary Python statements from C?
5.4.  How can I evaluate an arbitrary Python expression from C?
5.5.  How do I extract C values from a Python object?
5.6.  How do I use Py_BuildValue() to create a tuple of arbitrary
      length?
5.7.  How do I call an object's method from C?
5.8.  How do I catch the output from PyErr_Print() (or anything that
      prints to stdout/stderr)?
5.9.  How do I access a module written in Python from C?
5.10. How do I interface to C++ objects from Python?
5.11. mSQLmodule (or other old module) won't build with Python 1.5 (or
      later)
5.12. I added a module using the Setup file and the make fails! Huh?
5.13. I want to compile a Python module on my Red Hat Linux system, but
      some files are missing.
5.14. What does "SystemError: _PyImport_FixupExtension: module
      yourmodule not loaded" mean?

----------------------------------------------------------------------------

6. Python's design

6.1.  Why isn't there a switch or case statement in Python?
6.2.  Why does Python use indentation for grouping of statements?
6.3.  Why are Python strings immutable?
6.4.  Why don't strings have methods like index() or sort(), like lists?
6.5.  Why does Python use methods for some functionality (e.g.
      list.index()) but functions for other (e.g. len(list))?
6.6.  Why can't I derive a class from built-in types (e.g. lists or
      files)?
6.7.  Why must 'self' be declared and used explicitly in method
      definitions and calls?
6.8.  Can't you emulate threads in the interpreter instead of relying on
      an OS-specific thread implementation?
6.9.  Why can't lambda forms contain statements?
6.10. Why don't lambdas have access to variables defined in the
      containing scope?
6.11. Why can't recursive functions be defined inside other functions?
6.12. Why is there no more efficient way of iterating over a dictionary
      than first constructing the list of keys()?
6.13. Can Python be compiled to machine code, C or some other language?
6.14. How does Python manage memory? Why not full garbage collection?
6.15. Why are there separate tuple and list data types?
6.16. How are lists implemented?
6.17. How are dictionaries implemented?
6.18. Why must dictionary keys be immutable?
6.19. How the heck do you make an array in Python?
6.20. Why doesn't list.sort() return the sorted list?
6.21. How do you specify and enforce an interface spec in Python?
6.22. Why do all classes have the same type? Why do instances all have
      the same type?
6.23. Why isn't all memory freed when Python exits?
6.24. Why no class methods or mutable class variables?
6.25. Why are default values sometimes shared between objects?
6.26. Why no goto?
6.27. How do you make a higher order function in Python?
6.28. Why do I get a SyntaxError for a 'continue' inside a 'try'?
6.29. Why can't raw strings (r-strings) end with a backslash?
6.30. Why can't I use an assignment in an expression?

----------------------------------------------------------------------------

7. Using Python on non-UNIX platforms

7.1.  Is there a Mac version of Python?
7.2.  Are there DOS and Windows versions of Python?
7.3.  Is there an OS/2 version of Python?
7.4.  Is there a VMS version of Python?
7.5.  What about IBM mainframes, or other non-UNIX platforms?
7.6.  Where are the source or Makefiles for the non-UNIX versions?
7.7.  What is the status and support for the non-UNIX versions?
7.8.  I have a PC version but it appears to be only a binary. Where's
      the library?
7.9.  Where's the documentation for the Mac or PC version?
7.10. How do I create a Python program file on the Mac or PC?
7.11. How can I use Tkinter on Windows 95/NT?
7.12. cgi.py (or other CGI programming) doesn't work sometimes on NT or
      win95!
7.13. Why doesn't os.popen() work in PythonWin on NT?
7.14. How do I use different functionality on different platforms with
      the same program?
7.15. Is there an Amiga version of Python?
7.16. Why doesn't os.popen()/win32pipe.popen() work on Win9x?

----------------------------------------------------------------------------

8. Python on Windows

8.1.  Using Python for CGI on Microsoft Windows
8.2.  How to check for a keypress without blocking?
8.3.  $PYTHONPATH
8.4.  dedent syntax errors
8.5.  How do I emulate os.kill() in Windows?
8.6.  Why does os.path.isdir() fail on NT shared directories?
8.7.  PyRun_SimpleFile() crashes on Windows but not on Unix
8.8.  Import of _tkinter fails on Windows 95/98
8.9.  Can't extract the downloaded documentation on Windows
8.10. Can't get Py_RunSimpleFile() to work.
8.11. Where is Freeze for Windows?
8.12. Is a *.pyd file the same as a DLL?
8.13. Missing cw3215mt.dll (or missing cw3215.dll)

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:10 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:10 GMT
Subject: Python Language FAQ - Section 1
Message-ID: <mt2.0-6734-931390030@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 1

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

1. General information and availability

1.1.  What is Python?
1.2.  Why is it called Python?
1.3.  How do I obtain a copy of the Python source?
1.4.  How do I get documentation on Python?
1.5.  Are there other ftp sites that mirror the Python distribution?
1.6.  Is there a newsgroup or mailing list devoted to Python?
1.7.  Is there a WWW page devoted to Python?
1.8.  Is the Python documentation available on the WWW?
1.9.  Are there any books on Python?
1.10. Are there any published articles about Python that I can
      reference?
1.11. Are there short introductory papers or talks on Python?
1.12. How does the Python version numbering scheme work?
1.13. How do I get a beta test version of Python?
1.14. Are there copyright restrictions on the use of Python?
1.15. Why was Python created in the first place?
1.16. Do I have to like "Monty Python's Flying Circus"?
1.17. What is Python good for?
1.18. Can I use the FAQ Wizard software to maintain my own FAQ?
1.19. Which editor has good support for editing Python source code?

----------------------------------------------------------------------------

1. General information and availability

----------------------------------------------------------------------------

1.1. What is Python?

Python is an interpreted, interactive, object-oriented programming language.
It incorporates modules, exceptions, dynamic typing, very high level dynamic
data types, and classes. Python combines remarkable power with very clear
syntax. It has interfaces to many system calls and libraries, as well as to
various window systems, and is extensible in C or C++. It is also usable as
an extension language for applications that need a programmable interface.
Finally, Python is portable: it runs on many brands of UNIX, on the Mac, and
on PCs under MS-DOS, Windows, Windows NT, and OS/2.

To find out more, the best thing to do is to start reading the tutorial from
the documentation set (see a few questions further down).

See also question 1.17 (what is Python good for).

----------------------------------------------------------------------------

1.2. Why is it called Python?

Apart from being a computer scientist, I'm also a fan of "Monty Python's
Flying Circus" (a BBC comedy series from the seventies, in the -- unlikely
-- case you didn't know). It occurred to me one day that I needed a name
that was short, unique, and slightly mysterious. And I happened to be
reading some scripts from the series at the time... So then I decided to
call my language Python. But Python is not a joke. And don't you associate
it with dangerous reptiles either! (If you need an icon, use an image of the
16-ton weight from the TV series or of a can of SPAM :-)

----------------------------------------------------------------------------

1.3. How do I obtain a copy of the Python source?

The latest complete Python source distribution is always available by
anonymous ftp, e.g. ftp://ftp.python.org/pub/python/src/python1.4.tar.gz. It
is a gzipped tar file containing the complete C source, LaTeX documentation,
Python library modules, example programs, and several useful pieces of
freely distributable software. This will compile and run out of the box on
most UNIX platforms. (See section 7 for non-UNIX information.)

An index of said ftp directory can be found in the file INDEX. An HTML
version of the index can be found in the file index.html,
ftp://ftp.python.org/pub/python/index.html.

----------------------------------------------------------------------------

1.4. How do I get documentation on Python?

All documentation is available on-line, starting at
http://www.python.org/doc/.

The LaTeX source for the documentation is part of the source distribution.
If you don't have LaTeX, the latest Python documentation set is available,
in various formats like postscript and html, by anonymous ftp - visit the
above URL for links to the current versions.

PostScript for a high-level description of Python is in the file
nluug-paper.ps (a separate file on the ftp site).

----------------------------------------------------------------------------

1.5. Are there other ftp sites that mirror the Python distribution?

The following anonymous ftp sites keep mirrors of the Python distribution:

USA:

            ftp://ftp.python.org/pub/python/
            ftp://gatekeeper.dec.com/pub/plan/python/
            ftp://ftp.uu.net/languages/python/
            ftp://ftp.wustl.edu/graphics/graphics/sgi-stuff/python/
            ftp://ftp.sterling.com/programming/languages/python/
            ftp://uiarchive.cso.uiuc.edu/pub/lang/python/
            ftp://ftp.pht.com/mirrors/python/python/
            ftp://ftp.cdrom.com/pub/python/

Europe:

            ftp://ftp.cwi.nl/pub/python/
            ftp://ftp.funet.fi/pub/languages/python/
            ftp://ftp.sunet.se/pub/lang/python/
            ftp://unix.hensa.ac.uk/mirrors/uunet/languages/python/
            ftp://ftp.lip6.fr/pub/python/
            ftp://sunsite.cnlab-switch.ch/mirror/python/
            ftp://ftp.informatik.tu-muenchen.de/pub/comp/programming/languages/python/

Australia:

            ftp://ftp.dstc.edu.au/pub/python/

----------------------------------------------------------------------------

1.6. Is there a newsgroup or mailing list devoted to Python?

There is a newsgroup, comp.lang.python, and a mailing list. The newsgroup
and mailing list are gatewayed into each other -- if you can read news it's
unnecessary to subscribe to the mailing list. To subscribe to the mailing
list (python-list@python.org) visit its Mailman webpage at
http://www.python.org/mailman/listinfo/python-list

More info about the newsgroup and mailing list, and about other lists, can
be found at http://www.python.org/psa/MailingLists.html.

Archives of the newsgroup are kept by Deja News and accessible through the
"Python newsgroup search" web page,
http://www.python.org/search/search_news.html. This page also contains
pointer to other archival collections.

----------------------------------------------------------------------------

1.7. Is there a WWW page devoted to Python?

Yes, http://www.python.org/ is the official Python home page.

----------------------------------------------------------------------------

1.8. Is the Python documentation available on the WWW?

Yes, see http://www.python.org/ (Python's home page). It contains pointers
to hypertext versions of the whole documentation set (as hypertext, not just
PostScript).

If you wish to browse this collection of HTML files on your own machine, it
is available bundled up by anonymous ftp, e.g.
ftp://ftp.python.org/pub/python/doc/html.tar.gz.

An Emacs-INFO set containing the library manual is also available by ftp,
e.g. ftp://ftp.python.org/pub/python/doc/lib-info.tar.gz.

----------------------------------------------------------------------------

1.9. Are there any books on Python?

Yes, several:

          + Internet Programming with Python
            by Aaron Watters, Guido van Rossum, and James Ahlstrom
            MIS Press/Henry Holt publishers
            ISBN: 1-55851-484-8
            First published October, 1996

          + Programming Python
            by Mark Lutz
            O'Reilly & Associates
            ISBN: 1-56592-197-6
            First published October, 1996

          + Das Python-Buch (in German)
            by Martin von Loewis and Nils Fischbeck
            Addison-Wesley-Longman, 1997
            ISBN: 3-8273-1110-1

More are coming:

          + Python Pocket Reference
            by Mark Lutz
            O'Reilly & Associates
            ISBN 1-56592-500-9
            1st Edition October 1998 (est.)
            80 pages (est.), $6.95 (est.)

----------------------------------------------------------------------------

1.10. Are there any published articles about Python that I can reference?

If you can't reference the web site, and you don't want to reference the
books (see previous question), there are several articles on Python that you
could reference.

Most publications about Python are collected on the Python web site:

        http://www.python.org/doc/Publications.html

It is no longer recommended to reference this very old article by Python's
author:

        Guido van Rossum and Jelke de Boer, "Interactively Testing Remote
        Servers Using the Python Programming Language", CWI Quarterly, Volume
        4, Issue 4 (December 1991), Amsterdam, pp 283-303.

----------------------------------------------------------------------------

1.11. Are there short introductory papers or talks on Python?

There are several - you can find links to some of them collected at
http://www.python.org/doc/Hints.html#intros.

----------------------------------------------------------------------------

1.12. How does the Python version numbering scheme work?

Python versions are numbered A.B.C or A.B. A is the major version number --
it is only incremented for major changes in functionality or source
structure. B is the minor version number, incremented for less
earth-shattering changes to a release. C is the patchlevel -- it is
incremented for each new patch release. Not all releases have patch
releases. Note that in the past, patches have added significant changes; in
fact the changeover from 0.9.9 to 1.0.0 was the first time that either A or
B changed!

Beta versions have an additional suffix of "betaN" for some small number N.
Note that (for instance) all versions labeled 1.4betaN precede the actual
release of 1.4. 1.4b3 is short for 1.4beta3.

----------------------------------------------------------------------------

1.13. How do I get a beta test version of Python?

If there are any beta releases, they are published in the normal source
directory (e.g. ftp://ftp.python.org/pub/python/src/).

Alpha releases are only open to PSA members. See http://www.python.org/psa/
for information on how to join ($50/year).

----------------------------------------------------------------------------

1.14. Are there copyright restrictions on the use of Python?

Hardly. You can do anything you want with the source, as long as you leave
the copyrights in, and display those copyrights in any documentation about
Python that you produce. Also, don't use the author's institute's name in
publicity without prior written permission, and don't hold them responsible
for anything (read the actual copyright for a precise legal wording).

In particular, if you honor the copyright rules, it's OK to use Python for
commercial use, to sell copies of Python in source or binary form, or to
sell products that enhance Python or incorporate Python (or part of it) in
some form. I would still like to know about all commercial use of Python!

----------------------------------------------------------------------------

1.15. Why was Python created in the first place?

Here's a very brief summary of what got me started:

I had extensive experience with implementing an interpreted language in the
ABC group at CWI, and from working with this group I had learned a lot about
language design. This is the origin of many Python features, including the
use of indentation for statement grouping and the inclusion of
very-high-level data types (although the details are all different in
Python).

I had a number of gripes about the ABC language, but also liked many of its
features. It was impossible to extend the ABC language (or its
implementation) to remedy my complaints -- in fact its lack of extensibility
was one of its biggest problems. I had some experience with using Modula-2+
and talked with the designers of Modula-3 (and read the M3 report). M3 is
the origin of the syntax and semantics used for exceptions, and some other
Python features.

I was working in the Amoeba distributed operating system group at CWI. We
needed a better way to do system administration than by writing either C
programs or Bourne shell scripts, since Amoeba had its own system call
interface which wasn't easily accessible from the Bourne shell. My
experience with error handling in Amoeba made me acutely aware of the
importance of exceptions as a programming language feature.

It occurred to me that a scripting language with a syntax like ABC but with
access to the Amoeba system calls would fill the need. I realized that it
would be foolish to write an Amoeba-specific language, so I decided that I
needed a language that was generally extensible.

During the 1989 Christmas holidays, I had a lot of time on my hand, so I
decided to give it a try. During the next year, while still mostly working
on it in my own time, Python was used in the Amoeba project with increasing
success, and the feedback from colleagues made me add many early
improvements.

In February 1991, after just over a year of development, I decided to post
to USENET. The rest is in the Misc/HISTORY file.

----------------------------------------------------------------------------

1.16. Do I have to like "Monty Python's Flying Circus"?

No, but it helps. Pythonistas like the occasional reference to SPAM, and of
course, nobody expects the Spanish Inquisition

The two main reasons to use Python are:

     - Portable
     - Easy to learn

The three main reasons to use Python are:

     - Portable
     - Easy to learn
     - Powerful standard library

(And nice red uniforms.)

And remember, there is no rule six.

----------------------------------------------------------------------------

1.17. What is Python good for?

Python is used in many situations where a great deal of dynamism, ease of
use, power, and flexibility are required.

In the area of basic text manipulation core Python (without any non-core
extensions) is easier to use and is roughly as fast as just about any
language, and this makes Python good for many system administration type
tasks and for CGI programming and other application areas that manipulate
text and strings and such.

When augmented with standard extensions (such as PIL, COM, Numeric,
oracledb, kjbuckets, tkinter, win32api, etc.) or special purpose extensions
(that you write, perhaps using helper tools such as SWIG, or using object
protocols such as ILU/CORBA or COM) Python becomes a very convenient "glue"
or "steering" language that helps make heterogeneous collections of
unrelated software packages work together. For example by combining Numeric
with oracledb you can help your SQL database do statistical analysis, or
even Fourier transforms. One of the features that makes Python excel in the
"glue language" role is Python's simple, usable, and powerful C language
runtime API.

Many developers also use Python extensively as a graphical user interface
development aide.

----------------------------------------------------------------------------

1.18. Can I use the FAQ Wizard software to maintain my own FAQ?

Sure. Version 1.0 is distributed in the Tools subdirectory of the Python 1.5
source release at

      http://www.python.org/ftp/python/src/py152.tgz

----------------------------------------------------------------------------

1.19. Which editor has good support for editing Python source code?

On Unix, the first choice is Emacs/XEmacs. There's an elaborate mode for
editing Python code, which is available from the Python source distribution
(Misc/python-mode.el). It's also bundled with XEmacs (we're still working on
legal details to make it possible to bundle it with FSF Emacs). And it has
its own web page:

        http://www.python.org/emacs/python-mode/index.html

There are many other choices, for Unix, Windows or Macintosh. Richard Jones
compiled a table from postings on the Python newsgroup:

        http://www.bofh.asn.au/~richard/editors.html

See also FAQ question 7.10 for some more Mac and Win options.

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:23 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:23 GMT
Subject: Python Language FAQ - Section 3
Message-ID: <mt2.0-6734-931390043@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 3

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

3. Building Python and Other Known Bugs

3.1.  Is there a test set?
3.2.  When running the test set, I get complaints about floating point
      operations, but when playing with floating point operations I cannot
      find anything wrong with them.
3.3.  Link errors after rerunning the configure script.
3.4.  The python interpreter complains about options passed to a script
      (after the script name).
3.5.  When building on the SGI, make tries to run python to create
      glmodule.c, but python hasn't been built or installed yet.
3.6.  I use VPATH but some targets are built in the source directory.
3.7.  Trouble building or linking with the GNU readline library.
3.8.  Trouble with socket I/O on older Linux 1.x versions.
3.9.  Trouble with prototypes on Ultrix.
3.10. Other trouble building Python on platform X.
3.11. How to configure dynamic loading on Linux.
3.12. I can't get shared modules to work on Linux 2.0 (Slackware96)?
3.13. Trouble when making modules shared on Linux.
3.14. How to use threads on Linux.
3.15. Errors when linking with a shared library containing C++ code.
3.16. I built with tkintermodule.c enabled but get 'Tkinter not found'
3.17. I built with Tk 4.0 but Tkinter complains about the Tk version.
3.18. Compilation or link errors for the _tkinter module
3.19. I configured and built Python for Tcl/Tk but "import Tkinter"
      fails.
3.20. Tk doesn't work right on DEC Alpha.
3.21. Several common system calls are missing from the posix module.
3.22. ImportError: No module named string, on MS Windows.
3.23. Core dump on SGI when using the gl module.
3.24. "Initializer not a constant" while building DLL on MS-Windows
3.25. Output directed to a pipe or file disappears on Linux.
3.26. Syntax Errors all over the place in Linux with libc 5.4
3.27. Crash in XIO on Linux when using Tkinter.
3.28. How can I test if Tkinter is working?
3.29. Is there a way to get the interactive mode of the python
      interpreter to perform function/variable name completion?
3.30. Why is the Python interpreter not built as a shared library?
3.31. Build with GCC on Solaris 2.6 (SunOS 5.6) fails
3.32. Running "make clean" seems to leave problematic files that cause
      subsequent builds to fail.

----------------------------------------------------------------------------

3. Building Python and Other Known Bugs

----------------------------------------------------------------------------

3.1. Is there a test set?

Sure. You can run it after building with "make test", or you can run it
manuall with the command

            import test.autotest

In 1.4 or earlier, use

            import autotest

The test set doesn't test all features of Python, but it goes a long way to
confirm that Python is actually working.

NOTE: if "make test" fails, don't just mail the output to the newsgroup --
this doesn't give enough information to debug the problem. Instead, find out
which test fails, and run that test manually from an interactive
interpreter. For example, if "make test" reports that test_spam fails, try
this interactively:

            import test.test_spam

This generally produces more verbose output which can be diagnosed to debug
the problem.

----------------------------------------------------------------------------

3.2. When running the test set, I get complaints about floating point
operations, but when playing with floating point operations I cannot find
anything wrong with them.

The test set makes occasional unwarranted assumptions about the semantics of
C floating point operations. Until someone donates a better floating point
test set, you will have to comment out the offending floating point tests
and execute similar tests manually.

----------------------------------------------------------------------------

3.3. Link errors after rerunning the configure script.

It is generally necessary to run "make clean" after a configuration change.

----------------------------------------------------------------------------

3.4. The python interpreter complains about options passed to a script
(after the script name).

You are probably linking with GNU getopt, e.g. through -liberty. Don't. The
reason for the complaint is that GNU getopt, unlike System V getopt and
other getopt implementations, doesn't consider a non-option to be the end of
the option list. A quick (and compatible) fix for scripts is to add "--" to
the interpreter, like this:

            #! /usr/local/bin/python --

You can also use this interactively:

            python -- script.py [options]

Note that a working getopt implementation is provided in the Python
distribution (in Python/getopt.c) but not automatically used.

----------------------------------------------------------------------------

3.5. When building on the SGI, make tries to run python to create
glmodule.c, but python hasn't been built or installed yet.

Comment out the line mentioning glmodule.c in Setup and build a python
without gl first; install it or make sure it is in your $PATH, then edit the
Setup file again to turn on the gl module, and make again. You don't need to
do "make clean"; you do need to run "make Makefile" in the Modules
subdirectory (or just run "make" at the toplevel).

----------------------------------------------------------------------------

3.6. I use VPATH but some targets are built in the source directory.

On some systems (e.g. Sun), if the target already exists in the source
directory, it is created there instead of in the build directory. This is
usually because you have previously built without VPATH. Try running "make
clobber" in the source directory.

----------------------------------------------------------------------------

3.7. Trouble building or linking with the GNU readline library.

Consider using readline 2.0. Some hints:

You can use the GNU readline library to improve the interactive user
interface: this gives you line editing and command history when calling
python interactively. You need to configure and build the GNU readline
library before running the configure script. Its sources are no longer
distributed with Python; you can ftp them from any GNU mirror site, or from
its home site ftp://slc2.ins.cwru.edu/pub/dist/readline-2.0.tar.gz (or a
higher version number -- using version 1.x is not recommended). Pass the
Python configure script the option --with-readline=DIRECTORY where DIRECTORY
is the absolute pathname of the directory where you've built the readline
library. Some hints on building and using the readline library: On SGI IRIX
5, you may have to add the following to rldefs.h:

            #ifndef sigmask
            #define sigmask(sig) (1L << ((sig)-1))
            #endif

On most systems, you will have to add #include "rldefs.h" to the top of
several source files, and if you use the VPATH feature, you will have to add
dependencies of the form foo.o: foo.c to the Makefile for several values of
foo. The readline library requires use of the termcap library. A known
problem with this is that it contains entry points which cause conflicts
with the STDWIN and SGI GL libraries. The STDWIN conflict can be solved by
adding a line saying '#define werase w_erase' to the stdwin.h file (in the
STDWIN distribution, subdirectory H). The GL conflict has been solved in the
Python configure script by a hack that forces use of the static version of
the termcap library. Check the newsgroup gnu.bash.bug news:gnu.bash.bug for
specific problems with the readline library (I don't read this group but
I've been told that it is the place for readline bugs).

----------------------------------------------------------------------------

3.8. Trouble with socket I/O on older Linux 1.x versions.

Once you've built Python, use it to run the regen.py script in the
Lib/linux1 directory. Apparently the files as distributed don't match the
system headers on some Linux versions.

----------------------------------------------------------------------------

3.9. Trouble with prototypes on Ultrix.

Ultrix cc seems broken -- use gcc, or edit config.h to #undef
HAVE_PROTOTYPES.

----------------------------------------------------------------------------

3.10. Other trouble building Python on platform X.

Please email the details to guido@cnri.reston.va.us and I'll look into it.
Please provide as many details as possible. In particular, if you don't tell
me what type of computer and what operating system (and version) you are
using it will be difficult for me to figure out what is the matter. If you
get a specific error message, please email it to me too.

----------------------------------------------------------------------------

3.11. How to configure dynamic loading on Linux.

This is now automatic as long as your Linux version uses the ELF object
format (all recent Linuxes do).

----------------------------------------------------------------------------

3.12. I can't get shared modules to work on Linux 2.0 (Slackware96)?

This is a bug in the Slackware96 release. The fix is simple: Make sure that
there is a link from /lib/libdl.so to /lib/libdl.so.1 so that the following
links are setup: /lib/libdl.so -> /lib/libdl.so.1 /lib/libdl.so.1 ->
/lib/libdl.so.1.7.14 You may have to rerun the configure script, after
rm'ing the config.cache file, before you attempt to rebuild python after
this fix.

----------------------------------------------------------------------------

3.13. Trouble when making modules shared on Linux.

This happens when you have built Python for static linking and then enable

      *shared*

in the Setup file. Shared library code must be compiled with "-fpic". If a
.o file for the module already exist that was compiled for static linking,
you must remove it or do "make clean" in the Modules directory.

----------------------------------------------------------------------------

3.14. How to use threads on Linux.

[Greg Stein] You need to have a very recent libc, or even better, get the
LinuxThreads-0.5 distribution. Note that if you install LinuxThreads
normally, then you shouldn't need to specify the directory to the
-with-thread configuration switch. The configure script ought to find it
without a problem. To make sure everything builds properly, do a "make
clean", remove config.cache, re-run configure with that switch, and then
build.

[Andy Dustman] On glibc systems (i.e. RedHat 5.0+), LinuxThreads is
obsoleted by POSIX threads (-lpthread). If you upgraded from an earlier
RedHat, remove LinuxThreads with "rpm -e linuxthreads linuxthreads-devel".
Then run configure using --with-thread as above.

----------------------------------------------------------------------------

3.15. Errors when linking with a shared library containing C++ code.

Link the main Python binary with C++. Change the definition of LINKCC in
Modules/Makefile to be your C++ compiler. You may have to edit config.c
slightly to make it compilable with C++.

----------------------------------------------------------------------------

3.16. I built with tkintermodule.c enabled but get 'Tkinter not found'

Tkinter.py (note: upper case T) lives in a subdirectory of Lib, Lib/tkinter.
If you are using the default module search path, you probably didn't enable
the line in the Modules/Setup file defining TKPATH; if you use the
environment variable PYTHONPATH, you'll have to add the proper tkinter
subdirectory.

For Windows, see question 7.11.

----------------------------------------------------------------------------

3.17. I built with Tk 4.0 but Tkinter complains about the Tk version.

Several things could cause this. You most likely have a Tk 3.6 installation
that wasn't completely eradicated by the Tk 4.0 installation (which tends to
add "4.0" to its installed files). You may have the Tk 3.6 support library
installed in the place where the Tk 4.0 support files should be (default
/usr/local/lib/tk/); you may have compiled Python with the old tk.h header
file (yes, this actually compiles!); you may actually have linked with Tk
3.6 even though Tk 4.0 is also around. Similar for Tcl 7.4 vs. Tcl 7.3.

----------------------------------------------------------------------------

3.18. Compilation or link errors for the _tkinter module

Most likely, there's a version mismatch between the Tcl/Tk header files
(tcl.h and tk.h) and the Tcl/Tk libraries you are using e.g. "-ltk8.0" and
"-ltcl8.0" arguments for _tkinter in the Setup file). It is possible to
install several versions of the Tcl/Tk libraries, but there can only be one
version of the tcl.h and tk.h header files. If the library doesn't match the
header, you'll get problems, either when linking the module, or when
importing it. Fortunately, the version number is clearly stated in each
file, so this is easy to find. Reinstalling and using the latest version
usually fixes the problem.

(Also note that when compiling unpatched Python 1.5.1 against Tcl/Tk 7.6/4.2
or older, you get an error on Tcl_Finalize. See the 1.5.1 patch page at
http://www.python.org/1.5/patches-1.5.1/.)

----------------------------------------------------------------------------

3.19. I configured and built Python for Tcl/Tk but "import Tkinter" fails.

Most likely, you forgot to enable the line in Setup that says
"TKPATH=:$(DESTLIB)/tkinter".

----------------------------------------------------------------------------

3.20. Tk doesn't work right on DEC Alpha.

You probably compiled either Tcl, Tk or Python with gcc. Don't. For this
platform, which has 64-bit integers, gcc is known to generate broken code.
The standard cc (which comes bundled with the OS!) works. If you still
prefer gcc, at least try recompiling with cc before reporting problems to
the newsgroup or the author; if this fixes the problem, report the bug to
the gcc developers instead. (As far as we know, there are no problem with
gcc on other platforms -- the instabilities seem to be restricted to the DEC
Alpha.) See also question 3.6.

There's also a 64-bit bugfix for Tcl/Tk; see

            http://grail.cnri.reston.va.us/grail/info/patches/tk64bit.txt

----------------------------------------------------------------------------

3.21. Several common system calls are missing from the posix module.

Most likely, all test compilations run by the configure script are failing
for some reason or another. Have a look in config.log to see what could be
the reason. A common reason is specifying a directory to the --with-readline
option that doesn't contain the libreadline.a file.

----------------------------------------------------------------------------

3.22. ImportError: No module named string, on MS Windows.

Most likely, your PYTHONPATH environment variable should be set to something
like:

set PYTHONPATH=c:\python;c:\python\lib;c:\python\scripts

(assuming Python was installed in c:\python)

----------------------------------------------------------------------------

3.23. Core dump on SGI when using the gl module.

There are conflicts between entry points in the termcap and curses libraries
and an entry point in the GL library. There's a hack of a fix for the
termcap library if it's needed for the GNU readline library, but it doesn't
work when you're using curses. Concluding, you can't build a Python binary
containing both the curses and gl modules.

----------------------------------------------------------------------------

3.24. "Initializer not a constant" while building DLL on MS-Windows

Static type object initializers in extension modules may cause compiles to
fail with an error message like "initializer not a constant". Fredrik Lundh
<Fredrik.Lundh@image.combitech.se> explains:

This shows up when building DLL under MSVC. There's two ways to address
this: either compile the module as C++, or change your code to something
like:

      statichere PyTypeObject bstreamtype = {
          PyObject_HEAD_INIT(NULL) /* must be set by init function */
          0,
          "bstream",
          sizeof(bstreamobject),

      ...

      void
      initbstream()
      {
          /* Patch object type */
          bstreamtype.ob_type = &PyType_Type;
          Py_InitModule("bstream", functions);
          ...
      }

----------------------------------------------------------------------------

3.25. Output directed to a pipe or file disappears on Linux.

Some people have reported that when they run their script interactively, it
runs great, but that when they redirect it to a pipe or file, no output
appears.

        % python script.py
        ...some output...
        % python script.py >file
        % cat file
        % # no output
        % python script.py | cat
        % # no output
        %

Nobody knows what causes this, but it is apparently a Linux bug. Most Linux
users are not affected by this.

There's at least one report of someone who reinstalled Linux (presumably a
newer version) and Python and got rid of the problem; so this may be the
solution.

----------------------------------------------------------------------------

3.26. Syntax Errors all over the place in Linux with libc 5.4

``I have installed python1.4 on my Linux system. When I try run the import
statement I get the following error message:''

       File "<stdin>", line 1
           import sys
              ^
       Syntax Error: "invalid syntax"

Did you compile it yourself? This usually is caused by an incompatibility
between libc 5.4.x and earlier libc's. In particular, programs compiled with
libc 5.4 give incorrect results on systems which had libc 5.2 installed
because the ctype.h file is broken. In this case, Python can't recognize
which characters are letters and so on. The fix is to install the C library
which was used when building the binary that you installed, or to compile
Python yourself. When you do this, make sure the C library header files
which get used by the compiler match the installed C library.

[adapted from an answer by Martin v. Loewis]

PS [adapted from Andreas Jung]: If you have upgraded to libc 5.4.x, and the
problem persists, check your library path for an older version of libc. Try
to clean update libc with the libs and the header files and then try to
recompile all.

----------------------------------------------------------------------------

3.27. Crash in XIO on Linux when using Tkinter.

When Python is built with threads under Linux, use of Tkinter can cause
crashes like the following:

      >>> from Tkinter import *
      >>> root = Tk()
      XIO:  fatal IO error 0 (Unknown error) on X server ":0.0"
            after 45 requests (40 known processed) with 1 events remaining.

The reason is that the default Xlib is not built with support for threads.
If you rebuild Xlib with threads enabled the problems go away.
Alternatively, you can rebuild Python without threads ("make clean" first!).

(Disclaimer: this is from memory.)

----------------------------------------------------------------------------

3.28. How can I test if Tkinter is working?

Try the following:

      python
      >>> import _tkinter
      >>> import Tkinter
      >>> Tkinter._test()

This should pop up a window with two buttons, one "Click me" and one "Quit".

If the first statement (import _tkinter) fails, your Python installation
probably has not been configured to support Tcl/Tk. On Unix, if you have
installed Tcl/Tk, you have to rebuild Python after editing the Modules/Setup
file to enable the _tkinter module and the TKPATH environment variable.

It is also possible to get complaints about Tcl/Tk version number mismatches
or missing TCL_LIBRARY or TK_LIBRARY environment variables. These have to do
with Tcl/Tk installation problems.

A common problem is to have installed versions of tcl.h and tk.h that don't
match the installed version of the Tcl/Tk libraries; this usually results in
linker errors or (when using dynamic loading) complaints about missing
symbols during loading the shared library.

----------------------------------------------------------------------------

3.29. Is there a way to get the interactive mode of the python interpreter
to perform function/variable name completion?

(From a posting by Guido van Rossum)

On Unix, if you have enabled the readline module (i.e. if Emacs-style
command line editing and bash-style history works for you), you can add this
by importing the undocumented standard library module "rlcompleter". When
completing a simple identifier, it completes keywords, built-ins and globals
in __main__; when completing NAME.NAME..., it evaluates (!) the expression
up to the last dot and completes its attributes.

This way, you can do "import string", type "string.", hit the completion key
twice, and see the list of names defined by the string module.

Tip: to use the tab key as the completion key, call

        readline.parse_and_bind("tab: complete")

You can put this in a ~/.pythonrc file, and set the PYTHONSTARTUP
environment variable to ~/.pythonrc. This will cause the completion to be
enabled whenever you run Python interactively.

Notes (see the docstring for rlcompleter.py for more information):

* The evaluation of the NAME.NAME... form may cause arbitrary application
defined code to be executed if an object with a __getattr__ hook is found.
Since it is the responsibility of the application (or the user) to enable
this feature, I consider this an acceptable risk. More complicated
expressions (e.g. function calls or indexing operations) are not evaluated.

* GNU readline is also used by the built-in functions input() and
raw_input(), and thus these also benefit/suffer from the complete features.
Clearly an interactive application can benefit by specifying its own
completer function and using raw_input() for all its input.

* When stdin is not a tty device, GNU readline is never used, and this
module (and the readline module) are silently inactive.

----------------------------------------------------------------------------

3.30. Why is the Python interpreter not built as a shared library?

(This is a Unix question; on Mac and Windows, it is a shared library.)

It's just a nightmare to get this to work on all different platforms. Shared
library portability is a pain. And yes, I know about GNU libtool -- but it
requires me to use its conventions for filenames etc, and it would require a
complete and utter rewrite of all the makefile and config tools I'm
currently using.

In practice, few applications embed Python -- it's much more common to have
Python extensions, which already are shared libraries. Also, serious
embedders often want total control over which Python version and
configuration they use so they wouldn't want to use a standard shared
library anyway. So while the motivation of saving space when lots of apps
embed Python is nice in theory, I doubt that it will save much in practice.
(Hence the low priority I give to making a shared library.)

----------------------------------------------------------------------------

3.31. Build with GCC on Solaris 2.6 (SunOS 5.6) fails

If you have upgraded Solaris 2.5 or 2.5.1 to Solaris 2.6, but you have not
upgraded your GCC installation, the compile may fail, e.g. like this:

     In file included from /usr/include/sys/stream.h:26,
                      from /usr/include/netinet/in.h:38,
                      from /usr/include/netdb.h:96,
                      from ./socketmodule.c:121:
     /usr/include/sys/model.h:32: #error "No DATAMODEL_NATIVE specified"

Solution: rebuild GCC for Solaris 2.6. You might be able to simply re-run
fixincludes, but people have had mixed success with doing that.

----------------------------------------------------------------------------

3.32. Running "make clean" seems to leave problematic files that cause
subsequent builds to fail.

Use "make clobber" instead.

Use "make clean" to reduce the size of the source/build directory after
you're happy with your build and installation. If you have already tried to
build python and you'd like to start over, you should use "make clobber". It
does a "make clean" and also removes files such as the partially built
Python library from a previous build.

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:16 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:16 GMT
Subject: Python Language FAQ - Section 2
Message-ID: <mt2.0-6734-931390035@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 2

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

2. Python in the real world

2.1.  How many people are using Python?
2.2.  Have any significant projects been done in Python?
2.3.  Are there any commercial projects going on using Python?
2.4.  How stable is Python?
2.5.  What new developments are expected for Python in the future?
2.6.  Is it reasonable to propose incompatible changes to Python?
2.7.  What is the future of Python?
2.8.  What is the PSA, anyway?
2.9.  How do I join the PSA?
2.10. What are the benefits of joining the PSA?
2.11. Is Python Y2K (Year 2000) Compliant?

----------------------------------------------------------------------------

2. Python in the real world

----------------------------------------------------------------------------

2.1. How many people are using Python?

I don't know, but the maximum number of simultaneous subscriptions to the
Python mailing list before it was gatewayed into the newsgroup was about 180
(several of which were local redistribution lists). I believe that many
active Python users don't bother to subscribe to the list, and now that
there's a newsgroup the mailing list subscription is even less meaningful. I
see new names on the newsgroup all the time and my best guess is that there
are currently at least several thousands of users.

Another statistic is the number of accesses to the Python WWW server. Have a
look at http://www.python.org/stats/.

----------------------------------------------------------------------------

2.2. Have any significant projects been done in Python?

At CWI (the former home of Python), we have written a 20,000 line authoring
environment for transportable hypermedia presentations, a 5,000 line
multimedia teleconferencing tool, as well as many many smaller programs.

At CNRI (Python's new home), we have written two large applications: Grail,
a fully featured web browser (see http://grail.cnri.reston.va.us), and the
Knowbot Operating Environment, a distributed environment for mobile code.

The University of Virginia uses Python to control a virtual reality engine.
See http://alice.cs.cmu.edu.

The ILU project at Xerox PARC can generate Python glue for ILU interfaces.
See ftp://ftp.parc.xerox.com/pub/ilu/ilu.html. ILU is a free CORBA compliant
ORB which supplies distributed object connectivity to a host of platforms
using a host of languages.

Mark Hammond and Greg Stein and others are interfacing Python to Microsoft's
COM and ActiveX architectures. This means, among other things, that Python
may be used in active server pages or as a COM controller (for example to
automatically extract from or insert information into Excel or MSAccess or
any other COM aware application). Mark claims Python can even be a ActiveX
scripting host (which means you could embed JScript inside a Python
application, if you had a strange sense of humor). Python/AX/COM is
distributed as part of the PythonWin distribution.

The University of California, Irvine uses a student administration system
called TELE-Vision written entirely in Python. Contact: Ray Price
rlprice@uci.edu.

The Melbourne Cricket Ground (MCG) in Australia (a 100,000+ person venue)
has it's scoreboard system written largely in Python on MS Windows. Python
expressions are used to create almost every scoring entry that appears on
the board. The move to Python/C++ away from exclusive C++ has provided a
level of functionality that would simply not have been viable otherwise.

See also the next question.

If you have done a significant project in Python that you'd like to be
included in the list above, send me email!

----------------------------------------------------------------------------

2.3. Are there any commercial projects going on using Python?

Yes, there's lots of commercial activity using Python. See
http://www.python.org/psa/Users.html for a list.

----------------------------------------------------------------------------

2.4. How stable is Python?

Very stable. While the current version number would suggest it is in the
early stages of development, in fact new, stable releases (numbered 0.9.x
through 1.4) have been coming out roughly every 3 to 6 or 12 months for the
past four years.

----------------------------------------------------------------------------

2.5. What new developments are expected for Python in the future?

Follow the newsgroup discussions! The workshop proceedings
(http://www.python.org/workshops/) may also contain interesting looks into
the future.

----------------------------------------------------------------------------

2.6. Is it reasonable to propose incompatible changes to Python?

In general, no. There are already millions of lines of Python code around
the world, so any changes in the language that invalidates more than a very
small fraction of existing programs has to be frowned upon. Even if you can
provide a conversion program, there still is the problem of updating all
documentation. Providing a gradual upgrade path is the only way if a feature
has to be changed.

----------------------------------------------------------------------------

2.7. What is the future of Python?

If I knew, I'd be rich :-)

Seriously, the formation of the PSA (Python Software Activity, see
http://www.python.org/psa/) ensures some kind of support even in the
(unlikely!) event that I'd be hit by a bus (actually, here in the U.S., a
car accident would be more likely :-), were to join a nunnery, or would be
head-hunted. A large number of Python users have become experts at Python
programming as well as maintenance of the implementation, and would easily
fill the vacuum created by my disappearance.

In the meantime, I have no plans to disappear -- rather, I am committed to
improving Python, and my current benefactor, CNRI (see
http://www.cnri.reston.va.us) is just as committed to continue its support
of Python and the PSA. In fact, we have great plans for Python -- we just
can't tell yet!

----------------------------------------------------------------------------

2.8. What is the PSA, anyway?

The Python Software Activity http://www.python.org/psa/ was created by a
number of Python aficionados who want Python to be more than the product and
responsibility of a single individual. It has found a home at CNRI
http://www.cnri.reston.va.us. Anybody who wishes Python well should join the
PSA.

----------------------------------------------------------------------------

2.9. How do I join the PSA?

The full scoop is available on the web, see
http://www.python.org/psa/regtempl.html. Summary: send a check of at least
$50 to CNRI/PSA, 1895 Preston White Drive, Suite 100, in Reston, VA 20191.
Full-time students pay $25. Prices drop by half the second half of the
fiscal year (April - September). Companies can join for a mere $500. Pets
may join for only $15!

----------------------------------------------------------------------------

2.10. What are the benefits of joining the PSA?

Like National Public Radio, without your support, Python will wither.

If you join, your name will be mentioned on the PSA's web server. Workshops
organized by the PSA http://www.python.org/workshops/ are only accessible to
PSA members (you can join at the door). The PSA is working on additional
benefits, such as reduced prices for books and software, and early access to
alpha versions of Python. (The latter has been realized -- the 1.5 alpha
testing program is accessible only to PSA members.)

You might also consider to become a member of the starship project. It is a
free group of Python enthusiasts, and you get a free account. They just
happen to admit only PSA members. Check out http://starship.python.net for
further information.

----------------------------------------------------------------------------

2.11. Is Python Y2K (Year 2000) Compliant?

Since Python is available free of charge, I don't want to make any absolute
guarantees. If there is a problem that I didn't foresee, I don't want to be
sued for damages.

That said, I'm pretty convinced that there are no Y2K problems anywhere in
the core distribution, either 1.5 or 1.4. Python does few date
manipulations, and what it does is all based on the Unix representation for
time (even on non-Unix systems) which uses seconds since 1970 and won't
overflow until 2038.

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:48 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:48 GMT
Subject: Python Language FAQ - Section 5
Message-ID: <mt2.0-6734-931390068@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 5

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

5. Extending Python

5.1.  Can I create my own functions in C?
5.2.  Can I create my own functions in C++?
5.3.  How can I execute arbitrary Python statements from C?
5.4.  How can I evaluate an arbitrary Python expression from C?
5.5.  How do I extract C values from a Python object?
5.6.  How do I use Py_BuildValue() to create a tuple of arbitrary
      length?
5.7.  How do I call an object's method from C?
5.8.  How do I catch the output from PyErr_Print() (or anything that
      prints to stdout/stderr)?
5.9.  How do I access a module written in Python from C?
5.10. How do I interface to C++ objects from Python?
5.11. mSQLmodule (or other old module) won't build with Python 1.5 (or
      later)
5.12. I added a module using the Setup file and the make fails! Huh?
5.13. I want to compile a Python module on my Red Hat Linux system, but
      some files are missing.
5.14. What does "SystemError: _PyImport_FixupExtension: module
      yourmodule not loaded" mean?

----------------------------------------------------------------------------

5. Extending Python

----------------------------------------------------------------------------

5.1. Can I create my own functions in C?

Yes, you can create built-in modules containing functions, variables,
exceptions and even new types in C. This is explained in the document
"Extending and Embedding the Python Interpreter" (the LaTeX file
Doc/ext.tex). Also read the chapter on dynamic loading.

There's more information on this in each of the Python books: Programming
Python, Internet Programming with Python, and Das Python-Buch (in German).

----------------------------------------------------------------------------

5.2. Can I create my own functions in C++?

Yes, using the C-compatibility features found in C++. Basically you place
extern "C" { ... } around the Python include files and put extern "C" before
each function that is going to be called by the Python interpreter. Global
or static C++ objects with constructors are probably not a good idea.

----------------------------------------------------------------------------

5.3. How can I execute arbitrary Python statements from C?

The highest-level function to do this is PyRun_SimpleString() which takes a
single string argument which is executed in the context of module __main__
and returns 0 for success and -1 when an exception occurred (including
SyntaxError). If you want more control, use PyRun_String(); see the source
for PyRun_SimpleString() in Python/pythonrun.c.

----------------------------------------------------------------------------

5.4. How can I evaluate an arbitrary Python expression from C?

Call the function PyRun_String() from the previous question with the start
symbol eval_input (Py_eval_input starting with 1.5a1); it parses an
expression, evaluates it and returns its value.

----------------------------------------------------------------------------

5.5. How do I extract C values from a Python object?

That depends on the object's type. If it's a tuple, PyTupleSize(o) returns
its length and PyTuple_GetItem(o, i) returns its i'th item; similar for
lists with PyListSize(o) and PyList_GetItem(o, i). For strings,
PyString_Size(o) returns its length and PyString_AsString(o) a pointer to
its value (note that Python strings may contain null bytes so strlen() is
not safe). To test which type an object is, first make sure it isn't NULL,
and then use PyString_Check(o), PyTuple_Check(o), PyList_Check(o), etc.

There is also a high-level API to Python objects which is provided by the
so-called 'abstract' interface -- read Include/abstract.h for further
details. It allows for example interfacing with any kind of Python sequence
(e.g. lists and tuples) using calls like PySequence_Length(),
PySequence_GetItem(), etc.) as well as many other useful protocols.

----------------------------------------------------------------------------

5.6. How do I use Py_BuildValue() to create a tuple of arbitrary length?

You can't. Use t = PyTuple_New(n) instead, and fill it with objects using
PyTuple_SetItem(t, i, o) -- note that this "eats" a reference count of o.
Similar for lists with PyList_New(n) and PyList_SetItem(l, i, o). Note that
you must set all the tuple items to some value before you pass the tuple to
Python code -- PyTuple_New(n) initializes them to NULL, which isn't a valid
Python value.

----------------------------------------------------------------------------

5.7. How do I call an object's method from C?

Here's a function (untested) that might become part of the next release in
some form. It uses <stdarg.h> to allow passing the argument list on to
vmkvalue():

            object *call_method(object *inst, char *methodname, char *format, ...)
            {
                    object *method;
                    object *args;
                    object *result;
                    va_list va;
                    method = getattr(inst, methodname);
                    if (method == NULL) return NULL;
                    va_start(va, format);
                    args = vmkvalue(format, va);
                    va_end(va);
                    if (args == NULL) {
                            DECREF(method);
                            return NULL;
                    }
                    result = call_object(method, args);
                    DECREF(method);
                    DECREF(args);
                    return result;
            }

This works for any instance that has methods -- whether built-in or
user-defined. You are responsible for eventually DECREF'ing the return
value.

To call, e.g., a file object's "seek" method with arguments 10, 0 (assuming
the file object pointer is "f"):

            res = call_method(f, "seek", "(OO)", 10, 0);
            if (res == NULL) {
                    ... an exception occurred ...
            }
            else {
                    DECREF(res);
            }

Note that since call_object() always wants a tuple for the argument list, to
call a function without arguments, pass "()" for the format, and to call a
function with one argument, surround the argument in parentheses, e.g.
"(i)".

----------------------------------------------------------------------------

5.8. How do I catch the output from PyErr_Print() (or anything that prints
to stdout/stderr)?

(Due to Mark Hammond):

In Python code, define an object that supports the "write()" method.
Redirect sys.stdout and sys.stderr to this object. Call print_error, or just
allow the standard traceback mechanism to work. Then, the output will go
wherever your write() method sends it.

The easiest way to do this is to use the StringIO class in the standard
library.

Sample code and use for catching stdout:

            >>> class StdoutCatcher:
            ...  def __init__(self):
            ...   self.data = ''
            ...  def write(self, stuff):
            ...   self.data = self.data + stuff
            ...
            >>> import sys
            >>> sys.stdout = StdoutCatcher()
            >>> print 'foo'
            >>> print 'hello world!'
            >>> sys.stderr.write(sys.stdout.data)
            foo
            hello world!

----------------------------------------------------------------------------

5.9. How do I access a module written in Python from C?

You can get a pointer to the module object as follows:

            module = PyImport_ImportModule("<modulename>");

If the module hasn't been imported yet (i.e. it is not yet present in
sys.modules), this initializes the module; otherwise it simply returns the
value of sys.modules["<modulename>"]. Note that it doesn't enter the module
into any namespace -- it only ensures it has been initialized and is stored
in sys.modules.

You can then access the module's attributes (i.e. any name defined in the
module) as follows:

            attr = PyObject_GetAttrString(module, "<attrname>");

Calling PyObject_SetAttrString(), to assign to variables in the module, also
works.

----------------------------------------------------------------------------

5.10. How do I interface to C++ objects from Python?

Depending on your requirements, there are many approaches. To do this
manually, begin by reading the "Extending and Embedding" document
(Doc/ext.tex, see also http://www.python.org/doc/). Realize that for the
Python run-time system, there isn't a whole lot of difference between C and
C++ -- so the strategy to build a new Python type around a C structure
(pointer) type will also work for C++ objects.

A useful automated approach (which also works for C) is SWIG:
http://www.cs.utah.edu/~beazley/SWIG/.

----------------------------------------------------------------------------

5.11. mSQLmodule (or other old module) won't build with Python 1.5 (or
later)

Since python-1.4 "Python.h" will have the file includes needed in an
extension module. Backward compatibility is dropped after version 1.4 and
therefore mSQLmodule.c will not build as "allobjects.h" cannot be found. The
following change in mSQLmodule.c is harmless when building it with 1.4 and
necessary when doing so for later python versions:

Remove lines:

            #include "allobjects.h"
            #include "modsupport.h"

And insert instead:

            #include "Python.h"

You may also need to add

                    #include "rename2.h"

if the module uses "old names".

This may happen with other ancient python modules as well, and the same fix
applies.

----------------------------------------------------------------------------

5.12. I added a module using the Setup file and the make fails! Huh?

Setup must end in a newline, if there is no newline there it gets very sad.
Aside from this possibility, maybe you have other non-Python-specific
linkage problems.

----------------------------------------------------------------------------

5.13. I want to compile a Python module on my Red Hat Linux system, but some
files are missing.

Red Hat's RPM for Python doesn't include the /usr/lib/python1.x/config/
directory, which contains various files required for compiling Python
extensions. Install the python-devel RPM to get the necessary files.

----------------------------------------------------------------------------

5.14. What does "SystemError: _PyImport_FixupExtension: module yourmodule
not loaded" mean?

This means that you have created an extension module named "yourmodule", but
your module init function does not initialize with that name.

Every module init function will have a line similar to:

      module = Py_InitModule("yourmodule", yourmodule_functions);

If the string passed to this function is not the same name as your extenion
module, the SystemError will be raised.

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:55 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:55 GMT
Subject: Python Language FAQ - Section 7
Message-ID: <mt2.0-6734-931390075@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 7

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

7. Using Python on non-UNIX platforms

7.1.  Is there a Mac version of Python?
7.2.  Are there DOS and Windows versions of Python?
7.3.  Is there an OS/2 version of Python?
7.4.  Is there a VMS version of Python?
7.5.  What about IBM mainframes, or other non-UNIX platforms?
7.6.  Where are the source or Makefiles for the non-UNIX versions?
7.7.  What is the status and support for the non-UNIX versions?
7.8.  I have a PC version but it appears to be only a binary. Where's
      the library?
7.9.  Where's the documentation for the Mac or PC version?
7.10. How do I create a Python program file on the Mac or PC?
7.11. How can I use Tkinter on Windows 95/NT?
7.12. cgi.py (or other CGI programming) doesn't work sometimes on NT or
      win95!
7.13. Why doesn't os.popen() work in PythonWin on NT?
7.14. How do I use different functionality on different platforms with
      the same program?
7.15. Is there an Amiga version of Python?
7.16. Why doesn't os.popen()/win32pipe.popen() work on Win9x?

----------------------------------------------------------------------------

7. Using Python on non-UNIX platforms

----------------------------------------------------------------------------

7.1. Is there a Mac version of Python?

Yes, see the "mac" subdirectory of the distribution sites, e.g.
ftp://ftp.python.org/pub/python/mac/.

----------------------------------------------------------------------------

7.2. Are there DOS and Windows versions of Python?

Yes. The core windows binaries are available from
http://www.python.org/windows/. There is a plethora of Windows extensions
available, including a large number of not-always-compatible GUI toolkits.
The core binaries include the standard Tkinter GUI extension.

Most windows extensions can be found (or referenced) at
http://www.python.org/windows/

Windows 3.1/DOS support seems to have dropped off recently. You may need to
settle for an old version of Python one these platforms. One such port is
WPY

WPY: Ports to DOS, Windows 3.1(1), Windows 95, Windows NT and OS/2. Also
contains a GUI package that offers portability between Windows (not DOS) and
Unix, and native look and feel on both.
ftp://ftp.python.org/pub/python/wpy/.

----------------------------------------------------------------------------

7.3. Is there an OS/2 version of Python?

Yes, see the "pc" and "wpy" subdirectory of the distribution sites (see
above).

----------------------------------------------------------------------------

7.4. Is there a VMS version of Python?

Yes, there is a port of Python 1.4 to OpenVMS and a few ports of 1.2 to VMS.
See ftp://ftp.python.org/pub/python/contrib/Porting/vms/.

Uwe Zessin has ported Python 1.5.x to OpenVMS. See
http://decus.decus.de/~zessin/.

----------------------------------------------------------------------------

7.5. What about IBM mainframes, or other non-UNIX platforms?

I haven't heard about these, except I remember hearing about an OS/9 port
and a port to Vxworks (both operating systems for embedded systems). If
you're interested in any of this, go directly to the newsgroup and ask
there, you may find exactly what you need. For example, a port to MPE/iX 5.0
on HP3000 computers was just announced, see
http://www.allegro.com/software/.

----------------------------------------------------------------------------

7.6. Where are the source or Makefiles for the non-UNIX versions?

The standard sources can (almost) be used. Additional sources can be found
in the platform-specific subdirectories of the distribution.

----------------------------------------------------------------------------

7.7. What is the status and support for the non-UNIX versions?

I don't have access to most of these platforms, so in general I am dependent
on material submitted by volunteers. However I strive to integrate all
changes needed to get it to compile on a particular platform back into the
standard sources, so porting of the next version to the various non-UNIX
platforms should be easy.

----------------------------------------------------------------------------

7.8. I have a PC version but it appears to be only a binary. Where's the
library?

If you are running any version of Windows, then you have the wrong
distribution. The FAQ lists current Windows versions. Notably, Pythonwin and
wpy provide fully functional installations.

But if you are sure you have the only distribution with a hope of working on
your system, then...

You still need to copy the files from the distribution directory
"python/Lib" to your system. If you don't have the full distribution, you
can get the file lib<version>.tar.gz from most ftp sites carrying Python;
this is a subset of the distribution containing just those files, e.g.
ftp://ftp.python.org/pub/python/src/lib1.4.tar.gz.

Once you have installed the library, you need to point sys.path to it.
Assuming the library is in C:\misc\python\lib, the following commands will
point your Python interpreter to it (note the doubled backslashes -- you can
also use single forward slashes instead):

            >>> import sys
            >>> sys.path.insert(0, 'C:\\misc\\python\\lib')
            >>>

For a more permanent effect, set the environment variable PYTHONPATH, as
follows (talking to a DOS prompt):

            C> SET PYTHONPATH=C:\misc\python\lib

----------------------------------------------------------------------------

7.9. Where's the documentation for the Mac or PC version?

The documentation for the Unix version also applies to the Mac and PC
versions. Where applicable, differences are indicated in the text.

----------------------------------------------------------------------------

7.10. How do I create a Python program file on the Mac or PC?

Use an external editor. On the Mac, BBEdit seems to be a popular no-frills
text editor. I work like this: start the interpreter; edit a module file
using BBedit; import and test it in the interpreter; edit again in BBedit;
then use the built-in function reload() to re-read the imported module; etc.
In the 1.4 distribution you will find a BBEdit extension that makes life a
little easier: it can tell the interpreter to execute the current window.
See :Mac:Tools:BBPy:README.

Regarding the same question for the PC, Kurt Wm. Hemr writes: "While anyone
with a pulse could certainly figure out how to do the same on MS-Windows, I
would recommend the NotGNU Emacs clone for MS-Windows. Not only can you
easily resave and "reload()" from Python after making changes, but since
WinNot auto-copies to the clipboard any text you select, you can simply
select the entire procedure (function) which you changed in WinNot, switch
to QWPython, and shift-ins to reenter the changed program unit."

If you're using Windows95 or Windows NT, you should also know about
PythonWin, which provides a GUI framework, with an mouse-driven editor, an
object browser, and a GUI-based debugger. See

           http://www.python.org/ftp/python/pythonwin/

for details.

----------------------------------------------------------------------------

7.11. How can I use Tkinter on Windows 95/NT?

Starting from Python 1.5, it's very easy -- just download and install Python
and Tcl/Tk and you're in business. See

      http://www.python.org/download/download_windows.html

One warning: don't attempt to use Tkinter from PythonWin (Mark Hammond's
IDE). Use it from the command line interface (python.exe) or the windowless
interpreter (pythonw.exe).

----------------------------------------------------------------------------

7.12. cgi.py (or other CGI programming) doesn't work sometimes on NT or
win95!

Be sure you have the latest python.exe, that you are using python.exe rather
than a GUI version of python and that you have configured the server to
execute

         "...\python.exe -u ..."

for the cgi execution. The -u (unbuffered) option on NT and win95 prevents
the interpreter from altering newlines in the standard input and output.
Without it post/multipart requests will seem to have the wrong length and
binary (eg, GIF) responses may get garbled (resulting in, eg, a "broken
image").

----------------------------------------------------------------------------

7.13. Why doesn't os.popen() work in PythonWin on NT?

The reason that os.popen() doesn't work from within PythonWin is due to a
bug in Microsoft's C Runtime Library (CRT). The CRT assumes you have a Win32
console attached to the process.

You should use the win32pipe module's popen() instead which doesn't depend
on having an attached Win32 console.

Example:

     import win32pipe
     f = win32pipe.popen('dir /c c:\\')
     print f.readlines()
     f.close()

----------------------------------------------------------------------------

7.14. How do I use different functionality on different platforms with the
same program?

Remember that Python is extremely dynamic and that you can use this dynamism
to configure a program at run-time to use available functionality on
different platforms. For example you can test the sys.platform and import
different modules based on its value.

       import sys
       if sys.platform == "win32":
          import win32pipe
          popen = win32pipe.popen
       else:
          import os
          popen = os.popen

(See FAQ 7.13 for an explanation of why you might want to do something like
this.) Also you can try to import a module and use a fallback if the import
fails:

        try:
             import really_fast_implementation
             choice = really_fast_implementation
        except ImportError:
             import slower_implementation
             choice = slower_implementation

----------------------------------------------------------------------------

7.15. Is there an Amiga version of Python?

Yes. See the AmigaPython homepage at
http://www.bigfoot.com/~irmen/python.html.

----------------------------------------------------------------------------

7.16. Why doesn't os.popen()/win32pipe.popen() work on Win9x?

There is a bug in Win9x that prevents os.popen/win32pipe.popen* from
working. The good news is there is a way to work around this problem. The
Microsoft Knowledge Base article that you need to lookup is: Q150956. You
will find links to the knowledge base at: http://www.microsoft.com/kb.

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:38 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:38 GMT
Subject: Python Language FAQ - Section 4
Message-ID: <mt2.0-6734-931390058@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 4

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

4. Programming in Python

4.1.  Is there a source code level debugger with breakpoints, step,
      etc.?
4.2.  Can I create an object class with some methods implemented in C
      and others in Python (e.g. through inheritance)? (Also phrased as: Can
      I use a built-in type as base class?)
4.3.  Is there a curses/termcap package for Python?
4.4.  Is there an equivalent to C's onexit() in Python?
4.5.  When I define a function nested inside another function, the
      nested function seemingly can't access the local variables of the outer
      function. What is going on? How do I pass local data to a nested
      function?
4.6.  How do I iterate over a sequence in reverse order?
4.7.  My program is too slow. How do I speed it up?
4.8.  When I have imported a module, then edit it, and import it again
      (into the same Python process), the changes don't seem to take place.
      What is going on?
4.9.  How do I find the current module name?
4.10. I have a module in which I want to execute some extra code when
      it is run as a script. How do I find out whether I am running as a
      script?
4.11. I try to run a program from the Demo directory but it fails with
      ImportError: No module named ...; what gives?
4.12. I have successfully built Python with STDWIN but it can't find
      some modules (e.g. stdwinevents).
4.13. What GUI toolkits exist for Python?
4.14. Are there any interfaces to database packages in Python?
4.15. Is it possible to write obfuscated one-liners in Python?
4.16. Is there an equivalent of C's "?:" ternary operator?
4.17. My class defines __del__ but it is not called when I delete the
      object.
4.18. How do I change the shell environment for programs called using
      os.popen() or os.system()? Changing os.environ doesn't work.
4.19. What is a class?
4.20. What is a method?
4.21. What is self?
4.22. What is an unbound method?
4.23. How do I call a method defined in a base class from a derived
      class that overrides it?
4.24. How do I call a method from a base class without using the name
      of the base class?
4.25. How can I organize my code to make it easier to change the base
      class?
4.26. How can I find the methods or attributes of an object?
4.27. I can't seem to use os.read() on a pipe created with os.popen().
4.28. How can I create a stand-alone binary from a Python script?
4.29. What WWW tools are there for Python?
4.30. How do I run a subprocess with pipes connected to both input and
      output?
4.31. How do I call a function if I have the arguments in a tuple?
4.32. How do I enable font-lock-mode for Python in Emacs?
4.33. Is there a scanf() or sscanf() equivalent?
4.34. Can I have Tk events handled while waiting for I/O?
4.35. How do I write a function with output parameters (call by
      reference)?
4.36. Please explain the rules for local and global variables in
      Python.
4.37. How can I have modules that mutually import each other?
4.38. How do I copy an object in Python?
4.39. How to implement persistent objects in Python? (Persistent ==
      automatically saved to and restored from disk.)
4.40. I try to use __spam and I get an error about
      _SomeClassName__spam.
4.41. How do I delete a file? And other file questions.
4.42. How to modify urllib or httplib to support HTTP/1.1?
4.43. Unexplicable syntax errors in compile() or exec.
4.44. How do I convert a string to a number?
4.45. How do I convert a number to a string?
4.46. How do I copy a file?
4.47. How do I check if an object is an instance of a given class or of
      a subclass of it?
4.48. What is delegation?
4.49. How do I test a Python program or component.
4.50. My multidimensional list (array) is broken! What gives?
4.51. I want to do a complicated sort: can you do a Schwartzian
      Transform in Python?
4.52. How to convert between tuples and lists?
4.53. Files retrieved with urllib contain leading garbage that looks
      like email headers.
4.54. How do I get a list of all instances of a given class?
4.55. A regular expression fails with regex.error: match failure.
4.56. I can't get signal handlers to work.
4.57. I can't use a global variable in a function? Help!
4.58. What's a negative index? Why doesn't list.insert() use them?
4.59. How can I sort one list by values from another list?
4.60. Why doesn't dir() work on builtin types like files and lists?
4.61. How can I mimic CGI form submission (METHOD=POST)?
4.62. If my program crashes with a bsddb (or anydbm) database open, it
      gets corrupted. How come?
4.63. How do I make a Python script executable on Unix?
4.64. How do you remove duplicates from a list?
4.65. Are there any known year 2000 problems in Python?
4.66. I want a version of map that applies a method to a sequence of
      objects! Help!
4.67. How do I generate random numbers in Python?
4.68. How do I access the serial (RS232) port?
4.69. Images on Tk-Buttons don't work in Py15?
4.70. Where is the math.py (socket.py, regex.py, etc.) source file?
4.71. How do I send mail from a Python script?
4.72. How do I avoid blocking in connect() of a socket?
4.73. How do I specify hexadecimal and octal integers?
4.74. How to get a single keypress at a time?
4.75. How can I overload constructors (or methods) in Python?
4.76. How do I pass keyword arguments from one method to another?
4.77. What module should I use to help with generating HTML?
4.78. How do I create documentation from doc strings?
4.79. How do I read (or write) binary data?
4.80. I can't get key bindings to work in Tkinter
4.81. "import crypt" fails
4.82. Are there coding standards or a style guide for Python programs?
4.83. How do I freeze Tkinter applications?
4.84. How do I create static class data and static class methods?
4.85. __import__('x.y.z') returns <module 'x'>; how do I get z?
4.86. Basic thread wisdom
4.87. Why doesn't closing sys.stdout (stdin, stderr) really close it?
4.88. What kinds of global value mutation are thread-safe?
4.89. How do I modify a string in place?
4.90. How to pass on keyword/optional parameters/arguments

----------------------------------------------------------------------------

4. Programming in Python

----------------------------------------------------------------------------

4.1. Is there a source code level debugger with breakpoints, step, etc.?

Yes. Check out module pdb. It is documented in the Library Reference Manual;
pdb.help() also prints the documentation. You can write your own debugger by
using the code for pdb as an example.

Pythonwin also has a GUI debugger available, based on bdb, which colors
breakpoints and has quite a few cool features (including debugging
non-Pythonwin programs). The interface needs some work, but is interesting
none the less. A reference can be found in
http://www.python.org/ftp/python/pythonwin/pwindex.html

Richard Wolff has created a modified version of pdb, called Pydb, for use
with the popular Data Display Debugger (DDD). Pydb can be found at
http://daikon.tuc.noao.edu/python/, and DDD can be found at
http://www.cs.tu-bs.de/softech/ddd/

----------------------------------------------------------------------------

4.2. Can I create an object class with some methods implemented in C and
others in Python (e.g. through inheritance)? (Also phrased as: Can I use a
built-in type as base class?)

No, but you can easily create a Python class which serves as a wrapper
around a built-in object, e.g. (for dictionaries):

            # A user-defined class behaving almost identical
            # to a built-in dictionary.
            class UserDict:
                    def __init__(self): self.data = {}
                    def __repr__(self): return repr(self.data)
                    def __cmp__(self, dict):
                            if type(dict) == type(self.data):
                                    return cmp(self.data, dict)
                            else:
                                    return cmp(self.data, dict.data)
                    def __len__(self): return len(self.data)
                    def __getitem__(self, key): return self.data[key]
                    def __setitem__(self, key, item): self.data[key] = item
                    def __delitem__(self, key): del self.data[key]
                    def keys(self): return self.data.keys()
                    def items(self): return self.data.items()
                    def values(self): return self.data.values()
                    def has_key(self, key): return self.data.has_key(key)

A2. See Jim Fulton's ExtensionClass for an example of a mechanism which
allows you to have superclasses which you can inherit from in Python -- that
way you can have some methods from a C superclass (call it a mixin) and some
methods from either a Python superclass or your subclass. See
http://www.digicool.com/papers/ExtensionClass.html.

----------------------------------------------------------------------------

4.3. Is there a curses/termcap package for Python?

[Andrew Kuchling] The standard Python distribution comes with a curses
module in the Modules/ subdirectory, though it's not compiled by default.
However, that module only supports plain curses; you can't use ncurses
features like colors with it (though it will link with ncurses).

Oliver Andrich has an enhanced module that does support such features;
there's a version available at
http://andrich.net/python/selfmade.html#ncursesmodule .

----------------------------------------------------------------------------

4.4. Is there an equivalent to C's onexit() in Python?

Yes, if you import sys and assign a function to sys.exitfunc, it will be
called when your program exits, is killed by an unhandled exception, or (on
UNIX) receives a SIGHUP or SIGTERM signal.

----------------------------------------------------------------------------

4.5. When I define a function nested inside another function, the nested
function seemingly can't access the local variables of the outer function.
What is going on? How do I pass local data to a nested function?

Python does not have arbitrarily nested scopes. When you need to create a
function that needs to access some data which you have available locally,
create a new class to hold the data and return a method of an instance of
that class, e.g.:

            class MultiplierClass:
                def __init__(self, factor):
                    self.factor = factor
                def multiplier(self, argument):
                    return argument * self.factor

            def generate_multiplier(factor):
                return MultiplierClass(factor).multiplier

            twice = generate_multiplier(2)
            print twice(10)
            # Output: 20

An alternative solution uses default arguments, e.g.:

            def generate_multiplier(factor):
                def multiplier(arg, fact = factor):
                    return arg*fact
                return multiplier

            twice = generate_multiplier(2)
            print twice(10)
            # Output: 20

----------------------------------------------------------------------------

4.6. How do I iterate over a sequence in reverse order?

If it is a list, the fastest solution is

            list.reverse()
            try:
                    for x in list:
                            "do something with x"
            finally:
                    list.reverse()

This has the disadvantage that while you are in the loop, the list is
temporarily reversed. If you don't like this, you can make a copy. This
appears expensive but is actually faster than other solutions:

            rev = list[:]
            rev.reverse()
            for x in rev:
                    <do something with x>

If it's not a list, a more general but slower solution is:

            for i in range(len(sequence)-1, -1, -1):
                    x = sequence[i]
                    <do something with x>

A more elegant solution, is to define a class which acts as a sequence and
yields the elements in reverse order (solution due to Steve Majewski):

            class Rev:
                    def __init__(self, seq):
                            self.forw = seq
                    def __len__(self):
                            return len(self.forw)
                    def __getitem__(self, i):
                            return self.forw[-(i + 1)]

You can now simply write:

            for x in Rev(list):
                    <do something with x>

Unfortunately, this solution is slowest of all, due to the method call
overhead...

----------------------------------------------------------------------------

4.7. My program is too slow. How do I speed it up?

That's a tough one, in general. There are many tricks to speed up Python
code; I would consider rewriting parts in C only as a last resort. One thing
to notice is that function and (especially) method calls are rather
expensive; if you have designed a purely OO interface with lots of tiny
functions that don't do much more than get or set an instance variable or
call another method, you may consider using a more direct way, e.g. directly
accessing instance variables. Also see the standard module "profile"
(described in the Library Reference manual) which makes it possible to find
out where your program is spending most of its time (if you have some
patience -- the profiling itself can slow your program down by an order of
magnitude).

Remember that many standard optimization heuristics you may know from other
programming experience may well apply to Python. For example it may be
faster to send output to output devices using larger writes rather than
smaller ones in order to avoid the overhead of kernel system calls. Thus CGI
scripts that write all output in "one shot" may be notably faster than those
that write lots of small pieces of output.

Also, be sure to use "aggregate" operations where appropriate. For example
the "slicing" feature allows programs to chop up lists and other sequence
objects in a single tick of the interpreter mainloop using highly optimized
C implementations. Thus to get the same effect as

      L2 = []
      for i in range[3]:
           L2.append(L1[i])

it is much shorter and far faster to use

      L2 = list(L1[:3]) # "list" is redundant if L1 is a list.

Note that the map() function, particularly used with builtin methods or
builtin functions can be a convenient accellerator. For example to pair the
elements of two lists together:

      >>> map(None, [1,2,3], [4,5,6])
      [(1, 4), (2, 5), (3, 6)]

or to compute a number of sines:

      >>> map( math.sin, (1,2,3,4))
      [0.841470984808, 0.909297426826, 0.14112000806,   -0.756802495308]

The map operation completes very quickly in such cases.

Other examples of aggregate operations include the join, joinfields, split,
and splitfields methods of the standard string builtin module. For example
if s1..s7 are large (10K+) strings then
string.joinfields([s1,s2,s3,s4,s5,s6,s7], "") may be far faster than the
more obvious s1+s2+s3+s4+s5+s6+s7, since the "summation" will compute many
subexpressions, whereas joinfields does all copying in one pass. For
manipulating strings also consider the regular expression libraries and the
"substitution" operations String % tuple and String % dictionary. Also be
sure to use the list.sort builtin method to do sorting, and see FAQ's 4.51
and 4.59 for examples of moderately advanced usage -- list.sort beats other
techniques for sorting in all but the most extreme circumstances.

There are many other aggregate operations available in the standard
libraries and in contributed libraries and extensions.

Another common trick is to "push loops into functions or methods." For
example suppose you have a program that runs slowly and you use the profiler
(profile.run) to determine that a Python function ff is being called lots of
times. If you notice that ff

       def ff(x):
           ...do something with x computing result...
           return result

tends to be called in loops like (A)

       list = map(ff, oldlist)

or (B)

       for x in sequence:
           value = ff(x)
           ...do something with value...

then you can often eliminate function call overhead by rewriting ff to

       def ffseq(seq):
           resultseq = []
           for x in seq:
               ...do something with x computing result...
               resultseq.append(result)
           return resultseq

and rewrite (A) to

        list = ffseq(oldlist)

and (B) to

        for value in ffseq(sequence):
            ...do something with value...

Other single calls ff(x) translate to ffseq([x])[0] with little penalty. Of
course this technique is not always appropriate and there are other
variants, which you can figure out.

You can gain some performance by explicitly storing the results of a
function or method lookup into a local variable. A loop like

        for key in token:
            dict[key] = dict.get(key, 0) + 1

resolves dict.get every iteration. If the method isn't going to change, a
faster implementation is

        dict_get = dict.get  # look up the method once
        for key in token:
            dict[key] = dict_get(key, 0) + 1

Default arguments can be used to determine values once, at compile time
instead of at run time. This can only be done for functions or objects which
will not be changed during program execution, such as replacing

        def degree_sin(deg):
            return math.sin(deg * math.pi / 180.0)

with

        def degree_sin(deg, factor = math.pi/180.0, sin = math.sin):
            return sin(deg * factor)

Because this trick uses default arguments for terms which should not be
changed, it should only be used when you are not concerned with presenting a
possibly confusing API to your users.

For an anecdote related to optimization, see

            http://www.python.org/doc/essays/list2str.html

----------------------------------------------------------------------------

4.8. When I have imported a module, then edit it, and import it again (into
the same Python process), the changes don't seem to take place. What is
going on?

For reasons of efficiency as well as consistency, Python only reads the
module file on the first time a module is imported. (Otherwise a program
consisting of many modules, each of which imports the same basic module,
would read the basic module over and over again.) To force rereading of a
changed module, do this:

            import modname
            reload(modname)

Warning: this technique is not 100% fool-proof. In particular, modules
containing statements like

            from modname import some_objects

will continue to work with the old version of the imported objects.

----------------------------------------------------------------------------

4.9. How do I find the current module name?

A module can find out its own module name by looking at the (predefined)
global variable __name__. If this has the value '__main__' you are running
as a script.

----------------------------------------------------------------------------

4.10. I have a module in which I want to execute some extra code when it is
run as a script. How do I find out whether I am running as a script?

See the previous question. E.g. if you put the following on the last line of
your module, main() is called only when your module is running as a script:

            if __name__ == '__main__': main()

----------------------------------------------------------------------------

4.11. I try to run a program from the Demo directory but it fails with
ImportError: No module named ...; what gives?

This is probably an optional module (written in C!) which hasn't been
configured on your system. This especially happens with modules like
"Tkinter", "stdwin", "gl", "Xt" or "Xm". For Tkinter, STDWIN and many other
modules, see Modules/Setup.in for info on how to add these modules to your
Python, if it is possible at all. Sometimes you will have to ftp and build
another package first (e.g. Tcl and Tk for Tkinter). Sometimes the module
only works on specific platforms (e.g. gl only works on SGI machines).

NOTE: if the complaint is about "Tkinter" (upper case T) and you have
already configured module "tkinter" (lower case t), the solution is not to
rename tkinter to Tkinter or vice versa. There is probably something wrong
with your module search path. Check out the value of sys.path.

For X-related modules (Xt and Xm) you will have to do more work: they are
currently not part of the standard Python distribution. You will have to ftp
the Extensions tar file, i.e.
ftp://ftp.python.org/pub/python/src/X-extension.tar.gz and follow the
instructions there.

See also the next question.

----------------------------------------------------------------------------

4.12. I have successfully built Python with STDWIN but it can't find some
modules (e.g. stdwinevents).

There's a subdirectory of the library directory named 'stdwin' which should
be in the default module search path. There's a line in Modules/Setup(.in)
that you have to enable for this purpose -- unfortunately in the latest
release it's not near the other STDWIN-related lines so it's easy to miss
it.

----------------------------------------------------------------------------

4.13. What GUI toolkits exist for Python?

Depending on what platform(s) you are aiming at, there are several.

Currently supported solutions:

There's a neat object-oriented interface to the Tcl/Tk widget set, called
Tkinter. It is part of the standard Python distribution and well-supported
-- all you need to do is build and install Tcl/Tk and enable the _tkinter
module and the TKPATH definition in Modules/Setup when building Python. This
is probably the easiest to install and use, and the most complete widget
set. It is also very likely that in the future the standard Python GUI API
will be based on or at least look very much like the Tkinter interface. For
more info about Tk, including pointers to the source, see the Tcl/Tk home
page at http://www.scriptics.com. Tcl/Tk is now fully portable to the Mac
and Windows platforms (NT and 95 only); you need Python 1.4beta3 or later
and Tk 4.1patch1 or later.

There's an interface to X11, including the Athena and Motif widget sets (and
a few individual widgets, like Mosaic's HTML widget and SGI's GL widget)
available from ftp://ftp.python.org/pub/python/src/X-extension.tar.gz.
Support by Sjoerd Mullender sjoerd@cwi.nl.

On top of the X11 interface there's the (recently revived) vpApp toolkit by
Per Spilling, now also maintained by Sjoerd Mullender sjoerd@cwi.nl. See
ftp://ftp.cwi.nl/pub/sjoerd/vpApp.tar.gz.

The Mac port has a rich and ever-growing set of modules that support the
native Mac toolbox calls. See the documentation that comes with the Mac
port. See ftp://ftp.python.org/pub/python/mac. Support by Jack Jansen
jack@cwi.nl.

The NT port supported by Mark Hammond MHammond@skippinet.com.au (see
question 7.2) includes an interface to the Microsoft Foundation Classes and
a Python programming environment using it that's written mostly in Python.
See ftp://ftp.python.org/pub/python/pythonwin/.

There's an object-oriented GUI based on the Microsoft Foundation Classes
model called WPY, supported by Jim Ahlstrom jim@interet.com. Programs
written in WPY run unchanged and with native look and feel on Windows NT/95,
Windows 3.1 (using win32s), and on Unix (using Tk). Source and binaries for
Windows and Linux are available in ftp://ftp.python.org/pub/python/wpy/.

Obsolete or minority solutions:

There's an interface to wxWindows. wxWindows is a portable GUI class library
written in C++. It supports XView, Motif, MS-Windows as targets. There is
some support for Macs and CURSES as well. wxWindows preserves the look and
feel of the underlying graphics toolkit. See the wxPython WWW page at
http://www.aiai.ed.ac.uk/~jacs/wx/wxpython/wxpython.html. Support for
wxPython (by Harri Pasanen pa@tekla.fi) appears to have a low priority.

For SGI IRIX only, there are unsupported interfaces to the complete GL
(Graphics Library -- low level but very good 3D capabilities) as well as to
FORMS (a buttons-and-sliders-etc package built on top of GL by Mark Overmars
-- ftp'able from ftp://ftp.cs.ruu.nl/pub/SGI/FORMS/). This is probably also
becoming obsolete, as OpenGL takes over.

There's an interface to STDWIN, a platform-independent low-level windowing
interface for Mac and X11. This is totally unsupported and rapidly becoming
obsolete. The STDWIN sources are at ftp://ftp.cwi.nl/pub/stdwin/. (For info
about STDWIN 2.0, please refer to Steven Pemberton steven@cwi.nl -- I
believe it is also dead.)

There is an interface to WAFE, a Tcl interface to the X11 Motif and Athena
widget sets. WAFE is at http://www.wu-wien.ac.at/wafe/wafe.html.

(The Fresco port that was mentioned in earlier versions of this FAQ no
longer seems to exist. Inquire with Mark Linton.)

----------------------------------------------------------------------------

4.14. Are there any interfaces to database packages in Python?

There's a whole collection of them in the contrib area of the ftp server,
see http://www.python.org/ftp/python/contrib/Database/.

----------------------------------------------------------------------------

4.15. Is it possible to write obfuscated one-liners in Python?

Yes. See the following three examples, due to Ulf Bartelt:

            # Primes < 1000
            print filter(None,map(lambda y:y*reduce(lambda x,y:x*y!=0,
            map(lambda x,y=y:y%x,range(2,int(pow(y,0.5)+1))),1),range(2,1000)))

            # First 10 Fibonacci numbers
            print map(lambda x,f=lambda x,f:(x<=1) or (f(x-1,f)+f(x-2,f)): f(x,f),
            range(10))

            # Mandelbrot set
            print (lambda Ru,Ro,Iu,Io,IM,Sx,Sy:reduce(lambda x,y:x+y,map(lambda y,
            Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,Sy=Sy,L=lambda yc,Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,i=IM,
            Sx=Sx,Sy=Sy:reduce(lambda x,y:x+y,map(lambda x,xc=Ru,yc=yc,Ru=Ru,Ro=Ro,
            i=i,Sx=Sx,F=lambda xc,yc,x,y,k,f=lambda xc,yc,x,y,k,f:(k<=0)or (x*x+y*y
            >=4.0) or 1+f(xc,yc,x*x-y*y+xc,2.0*x*y+yc,k-1,f):f(xc,yc,x,y,k,f):chr(
            64+F(Ru+x*(Ro-Ru)/Sx,yc,0,0,i)),range(Sx))):L(Iu+y*(Io-Iu)/Sy),range(Sy
            ))))(-2.1, 0.7, -1.2, 1.2, 30, 80, 24)
            #    \___ ___/  \___ ___/  |   |   |__ lines on screen
            #        V          V      |   |______ columns on screen
            #        |          |      |__________ maximum of "iterations"
            #        |          |_________________ range on y axis
            #        |____________________________ range on x axis

Don't try this at home, kids!

----------------------------------------------------------------------------

4.16. Is there an equivalent of C's "?:" ternary operator?

Not directly. In many cases you can mimic a?b:c with "a and b or c", but
there's a flaw: if b is zero (or empty, or None -- anything that tests
false) then c will be selected instead. In many cases you can prove by
looking at the code that this can't happen (e.g. because b is a constant or
has a type that can never be false), but in general this can be a problem.

Tim Peters (who wishes it was Steve Majewski) suggested the following
solution: (a and [b] or [c])[0]. Because [b] is a singleton list it is never
false, so the wrong path is never taken; then applying [0] to the whole
thing gets the b or c that you really wanted. Ugly, but it gets you there in
the rare cases where it is really inconvenient to rewrite your code using
'if'.

----------------------------------------------------------------------------

4.17. My class defines __del__ but it is not called when I delete the
object.

There are several possible reasons for this.

The del statement does not necessarily call __del__ -- it simply decrements
the object's reference count, and if this reaches zero __del__ is called.

If your data structures contain circular links (e.g. a tree where each child
has a parent pointer and each parent has a list of children) the reference
counts will never go back to zero. You'll have to define an explicit close()
method which removes those pointers. Please don't ever call __del__ directly
-- __del__ should call close() and close() should make sure that it can be
called more than once for the same object.

If the object has ever been a local variable (or argument, which is really
the same thing) to a function that caught an expression in an except clause,
chances are that a reference to the object still exists in that function's
stack frame as contained in the stack trace. Normally, deleting (better:
assigning None to) sys.exc_traceback will take care of this. If a stack was
printed for an unhandled exception in an interactive interpreter, delete
sys.last_traceback instead.

There is code that deletes all objects when the interpreter exits, but it is
not called if your Python has been configured to support threads (because
other threads may still be active). You can define your own cleanup function
using sys.exitfunc (see question 4.4).

Finally, if your __del__ method raises an exception, this will be ignored.
Starting with Python 1.4beta3, a warning message is printed to sys.stderr
when this happens.

See also question 6.14 for a discussion of the possibility of adding true
garbage collection to Python.

----------------------------------------------------------------------------

4.18. How do I change the shell environment for programs called using
os.popen() or os.system()? Changing os.environ doesn't work.

You must be using either a version of python before 1.4, or on a (rare)
system that doesn't have the putenv() library function.

Before Python 1.4, modifying the environment passed to subshells was left
out of the interpreter because there seemed to be no well-established
portable way to do it (in particular, some systems, have putenv(), others
have setenv(), and some have none at all). As of Python 1.4, almost all Unix
systems do have putenv(), and so does the Win32 API, and thus the os module
was modified so that changes to os.environ are trapped and the corresponding
putenv() call is made.

----------------------------------------------------------------------------

4.19. What is a class?

A class is the particular object type that is created by executing a class
statement. Class objects are used as templates, to create class instance
objects, which embody both the data structure and program routines specific
to a datatype.

----------------------------------------------------------------------------

4.20. What is a method?

A method is a function that you normally call as x.name(arguments...) for
some object x. The term is used for methods of classes and class instances
as well as for methods of built-in objects. (The latter have a completely
different implementation and only share the way their calls look in Python
code.) Methods of classes (and class instances) are defined as functions
inside the class definition.

----------------------------------------------------------------------------

4.21. What is self?

Self is merely a conventional name for the first argument of a method --
i.e. a function defined inside a class definition. A method defined as
meth(self, a, b, c) should be called as x.meth(a, b, c) for some instance x
of the class in which the definition occurs; the called method will think it
is called as meth(x, a, b, c).

----------------------------------------------------------------------------

4.22. What is an unbound method?

An unbound method is a method defined in a class that is not yet bound to an
instance. You get an unbound method if you ask for a class attribute that
happens to be a function. You get a bound method if you ask for an instance
attribute. A bound method knows which instance it belongs to and calling it
supplies the instance automatically; an unbound method only knows which
class it wants for its first argument (a derived class is also OK). Calling
an unbound method doesn't "magically" derive the first argument from the
context -- you have to provide it explicitly.

Trivia note regarding bound methods: each reference to a bound method of a
particular object creates a bound method object. If you have two such
references (a = inst.meth; b = inst.meth), they will compare equal (a == b)
but are not the same (a is not b).

----------------------------------------------------------------------------

4.23. How do I call a method defined in a base class from a derived class
that overrides it?

If your class definition starts with "class Derived(Base): ..." then you can
call method meth defined in Base (or one of Base's base classes) as
Base.meth(self, arguments...). Here, Base.meth is an unbound method (see
previous question).

----------------------------------------------------------------------------

4.24. How do I call a method from a base class without using the name of the
base class?

DON'T DO THIS. REALLY. I MEAN IT. It appears that you could call
self.__class__.__bases__[0].meth(self, arguments...) but this fails when a
doubly-derived method is derived from your class: for its instances,
self.__class__.__bases__[0] is your class, not its base class -- so
(assuming you are doing this from within Derived.meth) you would start a
recursive call.

Often when you want to do this you are forgetting that classes are first
class in Python. You can "point to" the class you want to delegate an
operation to either at the instance or at the subclass level. For example if
you want to use a "glorp" operation of a superclass you can point to the
right superclass to use.

      class subclass(superclass1, superclass2, superclass3):
          delegate_glorp = superclass2
          ...
          def glorp(self, arg1, arg2):
                ... subclass specific stuff ...
                self.delegate_glorp.glorp(self, arg1, arg2)
           ...

      class subsubclass(subclass):
           delegate_glorp = superclass3
           ...

Note, however that setting delegate_glorp to subclass in subsubclass would
cause an infinite recursion on subclass.delegate_glorp. Careful! Maybe you
are getting too fancy for your own good. Consider simplifying the design
(?).

----------------------------------------------------------------------------

4.25. How can I organize my code to make it easier to change the base class?

You could define an alias for the base class, assign the real base class to
it before your class definition, and use the alias throughout your class.
Then all you have to change is the value assigned to the alias.
Incidentally, this trick is also handy if you want to decide dynamically
(e.g. depending on availability of resources) which base class to use.
Example:

            BaseAlias = <real base class>
            class Derived(BaseAlias):
                    def meth(self):
                            BaseAlias.meth(self)
                            ...

----------------------------------------------------------------------------

4.26. How can I find the methods or attributes of an object?

This depends on the object type.

For an instance x of a user-defined class, instance attributes are found in
the dictionary x.__dict__, and methods and attributes defined by its class
are found in x.__class__.__bases__[i].__dict__ (for i in
range(len(x.__class__.__bases__))). You'll have to walk the tree of base
classes to find all class methods and attributes.

Many, but not all built-in types define a list of their method names in
x.__methods__, and if they have data attributes, their names may be found in
x.__members__. However this is only a convention.

For more information, read the source of the standard (but undocumented)
module newdir.

----------------------------------------------------------------------------

4.27. I can't seem to use os.read() on a pipe created with os.popen().

os.read() is a low-level function which takes a file descriptor (a small
integer). os.popen() creates a high-level file object -- the same type used
for sys.std{in,out,err} and returned by the builtin open() function. Thus,
to read n bytes from a pipe p created with os.popen(), you need to use
p.read(n).

----------------------------------------------------------------------------

4.28. How can I create a stand-alone binary from a Python script?

The "freeze" tool in "Tools/freeze/" does what you want. See the README.

This works by scanning your source recursively for import statements (both
forms) and looking for the modules on the standard Python path as well as in
the source directory (for built-in modules). It then "compiles" the modules
written in Python to C code (array initializers that can be turned into code
objects using the marshal module) and creates a custom-made config file that
only contains those built-in modules which are actually used in the program.
It then compiles the generated C code and links it with the rest of the
Python interpreter to form a self-contained binary which acts exactly like
your script.

Hint: the freeze program only works if your script's filename ends in ".py".

----------------------------------------------------------------------------

4.29. What WWW tools are there for Python?

See the chapter titled "Internet and WWW" in the Library Reference Manual.
There's also a web browser written in Python, called Grail -- see
http://grail.cnri.reston.va.us/grail/.

----------------------------------------------------------------------------

4.30. How do I run a subprocess with pipes connected to both input and
output?

Use the standard popen2 module. For example:

            import popen2
            fromchild, tochild = popen2.popen2("command")
            tochild.write("input\n")
            tochild.flush()
            output = fromchild.readline()

Warning: in general, it is unwise to do this, because you can easily cause a
deadlock where your process is blocked waiting for output from the child,
while the child is blocked waiting for input from you. This can be caused
because the parent expects the child to output more text than it does, or it
can be caused by data being stuck in stdio buffers due to lack of flushing.
The Python parent can of course explicitly flush the data it sends to the
child before it reads any output, but if the child is a naive C program it
can easily have been written to never explicitly flush its output, even if
it is interactive, since flushing is normally automatic.

Note on a bug in popen2: unless your program calls wait() or waitpid(),
finished child processes are never removed, and eventually calls to popen2
will fail because of a limit on the number of child processes. Calling
os.waitpid with the os.WNOHANG option can prevent this; a good place to
insert such a call would be before calling popen2 again.

In many cases, all you really need is to run some data through a command and
get the result back. Unless the data is infinite in size, the easiest (and
often the most efficient!) way to do this is to write it to a temporary file
and run the command with that temporary file as input. The standard module
tempfile exports a function mktemp() which generates unique temporary file
names.

Note that many interactive programs (e.g. vi) don't work well with pipes
substituted for standard input and output. You will have to use pseudo ttys
("ptys") instead of pipes. There is some undocumented code to use these in
the library module pty.py -- I'm afraid you're on your own here.

A different answer is a Python interface to Don Libes' "expect" library. A
Python extension that interfaces to expect is called "expy" and available
from ftp://ftp.python.org/pub/python/contrib/System/.

A pure Python solution that works like expect is PIPE by John Croix. A
prerelease of PIPE is available from
ftp://ftp.python.org/pub/python/contrib/System/.

----------------------------------------------------------------------------

4.31. How do I call a function if I have the arguments in a tuple?

Use the built-in function apply(). For instance,

        func(1, 2, 3)

is equivalent to

        args = (1, 2, 3)
        apply(func, args)

Note that func(args) is not the same -- it calls func() with exactly one
argument, the tuple args, instead of three arguments, the integers 1, 2 and
3.

----------------------------------------------------------------------------

4.32. How do I enable font-lock-mode for Python in Emacs?

If you are using XEmacs 19.14 or later, any XEmacs 20, FSF Emacs 19.34 or
any Emacs 20, font-lock should work automatically for you if you are using
the latest python-mode.el.

If you are using an older version of XEmacs or Emacs you will need to put
this in your .emacs file:

            (defun my-python-mode-hook ()
              (setq font-lock-keywords python-font-lock-keywords)
              (font-lock-mode 1))
            (add-hook 'python-mode-hook 'my-python-mode-hook)

----------------------------------------------------------------------------

4.33. Is there a scanf() or sscanf() equivalent?

Not as such.

For simple input parsing, the easiest approach is usually to split the line
into whitespace-delimited words using string.split(), and to convert decimal
strings to numeric values using string.atoi(), string.atol() or
string.atof(). (Python's atoi() is 32-bit and its atol() is arbitrary
precision.) If you want to use another delimiter than whitespace, use
string.splitfield() (possibly combining it with string.strip() which removes
surrounding whitespace from a string).

For more complicated input parsing, regular expressions (see module regex)
are better suited and more powerful than C's sscanf().

There's a contributed module that emulates sscanf(), by Steve Clift; see
contrib/Misc/sscanfmodule.c of the ftp site:

        http://www.python.org/ftp/python/contrib/Misc/sscanfmodule.c

----------------------------------------------------------------------------

4.34. Can I have Tk events handled while waiting for I/O?

Yes, and you don't even need threads! But you'll have to restructure your
I/O code a bit. Tk has the equivalent of Xt's XtAddInput() call, which
allows you to register a callback function which will be called from the Tk
mainloop when I/O is possible on a file descriptor. Here's what you need:

            from Tkinter import tkinter
            tkinter.createfilehandler(file, mask, callback)

The file may be a Python file or socket object (actually, anything with a
fileno() method), or an integer file descriptor. The mask is one of the
constants tkinter.READABLE or tkinter.WRITABLE. The callback is called as
follows:

            callback(file, mask)

You must unregister the callback when you're done, using

            tkinter.deletefilehandler(file)

Note: since you don't know *how many bytes* are available for reading, you
can't use the Python file object's read or readline methods, since these
will insist on reading a predefined number of bytes. For sockets, the recv()
or recvfrom() methods will work fine; for other files, use
os.read(file.fileno(), maxbytecount).

----------------------------------------------------------------------------

4.35. How do I write a function with output parameters (call by reference)?

[Mark Lutz] The thing to remember is that arguments are passed by assignment
in Python. Since assignment just creates references to objects, there's no
alias between an argument name in the caller and callee, and so no
call-by-reference per se. But you can simulate it in a number of ways:

1) By using global variables; but you probably shouldn't :-)

2) By passing a mutable (changeable in-place) object:

          def func1(a):
              a[0] = 'new-value'     # 'a' references a mutable list
              a[1] = a[1] + 1        # changes a shared object

          args = ['old-value', 99]
          func1(args)
          print args[0], args[1]     # output: new-value 100

3) By returning a tuple, holding the final values of arguments:

          def func2(a, b):
              a = 'new-value'        # a and b are local names
              b = b + 1              # assigned to new objects
              return a, b            # return new values

          x, y = 'old-value', 99
          x, y = func2(x, y)
          print x, y                 # output: new-value 100

4) And other ideas that fall-out from Python's object model. For instance,
it might be clearer to pass in a mutable dictionary:

          def func3(args):
              args['a'] = 'new-value'     # args is a mutable dictionary
              args['b'] = args['b'] + 1   # change it in-place

          args = {'a':' old-value', 'b': 99}
          func3(args)
          print args['a'], args['b']

5) Or bundle-up values in a class instance:

          class callByRef:
              def __init__(self, **args):
                  for (key, value) in args.items():
                      setattr(self, key, value)

          def func4(args):
              args.a = 'new-value'        # args is a mutable callByRef
              args.b = args.b + 1         # change object in-place

          args = callByRef(a='old-value', b=99)
          func4(args)
          print args.a, args.b

       But there's probably no good reason to get this complicated :-).

[Python's author favors solution 3 in most cases.]

----------------------------------------------------------------------------

4.36. Please explain the rules for local and global variables in Python.

[Ken Manheimer] In Python, procedure variables are implicitly global, unless
they are assigned anywhere within the block. In that case they are
implicitly local, and you need to explicitly declare them as 'global'.

Though a bit surprising at first, a moment's consideration explains this. On
one hand, requirement of 'global' for assigned vars provides a bar against
unintended side-effects. On the other hand, if global were required for all
global references, you'd be using global all the time. Eg, you'd have to
declare as global every reference to a builtin function, or to a component
of an imported module. This clutter would defeat the usefulness of the
'global' declaration for identifying side-effects.

----------------------------------------------------------------------------

4.37. How can I have modules that mutually import each other?

Jim Roskind recommends the following order in each module:

First: all exports (like globals, functions, and classes that don't need
imported base classes).

Then: all import statements.

Finally: all active code (including globals that are initialized from
imported values).

Python's author doesn't like this approach much because the imports appear
in a strange place, but has to admit that it works. His recommended strategy
is to avoid all uses of "from <module> import *" (so everything from an
imported module is referenced as <module>.<name>) and to place all code
inside functions. Initializations of global variables and class variables
should use constants or built-in functions only.

----------------------------------------------------------------------------

4.38. How do I copy an object in Python?

There is no generic copying operation built into Python, however most object
types have some way to create a clone. Here's how for the most common
objects:

For immutable objects (numbers, strings, tuples), cloning is unnecessary
since their value can't change. For lists (and generally for mutable
sequence types), a clone is created by the expression l[:]. For
dictionaries, the following function returns a clone:

            def dictclone(o):
                n = {}
                for k in o.keys(): n[k] = o[k]
                return n

Finally, for generic objects, the "copy" module defines two functions for
copying objects. copy.copy(x) returns a copy as shown by the above rules.
copy.deepcopy(x) also copies the elements of composite objects. See the
section on this module in the Library Reference Manual.

----------------------------------------------------------------------------

4.39. How to implement persistent objects in Python? (Persistent ==
automatically saved to and restored from disk.)

The library module "pickle" now solves this in a very general way (though
you still can't store things like open files, sockets or windows), and the
library module "shelve" uses pickle and (g)dbm to create persistent mappings
containing arbitrary Python objects. For possibly better performance also
look for the latest version of the relatively recent cPickle module.

A more awkward way of doing things is to use pickle's little sister,
marshal. The marshal module provides very fast ways to store noncircular
basic Python types to files and strings, and back again. Although marshal
does not do fancy things like store instances or handle shared references
properly, it does run extremely fast. For example loading a half megabyte of
data may take less than a third of a second (on some machines). This often
beats doing something more complex and general such as using gdbm with
pickle/shelve.

----------------------------------------------------------------------------

4.40. I try to use __spam and I get an error about _SomeClassName__spam.

Variables with double leading underscore are "mangled" to provide a simple
but effective way to define class private variables. See the chapter "New in
Release 1.4" in the Python Tutorial.

----------------------------------------------------------------------------

4.41. How do I delete a file? And other file questions.

Use os.remove(filename) or os.unlink(filename); for documentation, see the
posix section of the library manual. They are the same, unlink() is simply
the Unix name for this function. In earlier versions of Python, only
os.unlink() was available.

To remove a directory, use os.rmdir(); use os.mkdir() to create one.

To rename a file, use os.rename().

To truncate a file, open it using f = open(filename, "r+"), and use
f.truncate(offset); offset defaults to the current seek position. (The "r+"
mode opens the file for reading and writing.) There's also os.ftruncate(fd,
offset) for files opened with os.open() -- for advanced Unix hacks only.

----------------------------------------------------------------------------

4.42. How to modify urllib or httplib to support HTTP/1.1?

Apply the following patch to the vanilla Python 1.4 httplib.py:

      41c41
      < replypat = regsub.gsub('\\.', '\\\\.', HTTP_VERSION) + \
  ---
      > replypat = regsub.gsub('\\.', '\\\\.', 'HTTP/1.[0-9]+') + \

----------------------------------------------------------------------------

4.43. Unexplicable syntax errors in compile() or exec.

When a statement suite (as opposed to an expression) is compiled by
compile(), exec or execfile(), it must end in a newline. In some cases, when
the source ends in an indented block it appears that at least two newlines
are required.

----------------------------------------------------------------------------

4.44. How do I convert a string to a number?

For integers, use the built-in int() function, e.g. int('144') == 144.
Similarly, long() converts from string to long integer, e.g. long('144') ==
144L; and float() to floating-point, e.g. float('144') == 144.0.

Note that these are restricted to decimal interpretation, so that
int('0144') == 144 and int('0x144') raises ValueError.

For greater flexibility, or before Python 1.5, import the module string and
use the string.atoi() function for integers, string.atol() for long
integers, or string.atof() for floating-point. E.g., string.atoi('100', 16)
== string.atoi('0x100', 0) == 256. See the library reference manual section
for the string module for more details.

While you could use the built-in function eval() instead of any of those,
this is not recommended, because someone could pass you a Python expression
that might have unwanted side effects (like reformatting your disk).

----------------------------------------------------------------------------

4.45. How do I convert a number to a string?

To convert, e.g., the number 144 to the string '144', use the built-in
function repr() or the backquote notation (these are equivalent). If you
want a hexadecimal or octal representation, use the built-in functions hex()
or oct(), respectively. For fancy formatting, use the % operator on strings,
just like C printf formats, e.g. "%04d" % 144 yields '0144' and "%.3f" %
(1/3.0) yields '0.333'. See the library reference manual for details.

----------------------------------------------------------------------------

4.46. How do I copy a file?

Most of the time this will do:

       infile = open("file.in", "rb")
       outfile = open("file.out", "wb")
       outfile.write(infile.read())

However for huge files you may want to do the reads/writes in pieces (or you
may have to), and if you dig deeper you may find other technical problems.

Unfortunately, there's no totally platform independent answer. On Unix, you
can use os.system() to invoke the "cp" command (see your Unix manual for how
it's invoked). On DOS or Windows, use os.system() to invoke the "COPY"
command. On the Mac, use macostools.copy(srcpath, dstpath). It will also
copy the resource fork and Finder info.

There's also the shutil module which contains a copyfile() function that
implements the copy loop; but in Python 1.4 and earlier it opens files in
text mode, and even in Python 1.5 it still isn't good enough for the
Macintosh: it doesn't copy the resource fork and Finder info.

----------------------------------------------------------------------------

4.47. How do I check if an object is an instance of a given class or of a
subclass of it?

If you are developing the classes from scratch it might be better to program
in a more proper object-oriented style -- instead of doing a different thing
based on class membership, why not use a method and define the method
differently in different classes?

However, there are some legitimate situations where you need to test for
class membership.

In Python 1.5, you can use the built-in function isinstance(obj, cls).

The following approaches can be used with earlier Python versions:

An unobvious method is to raise the object as an exception and to try to
catch the exception with the class you're testing for:

            def is_instance_of(the_instance, the_class):
                try:
                    raise the_instance
                except the_class:
                    return 1
                except:
                    return 0

This technique can be used to distinguish "subclassness" from a collection
of classes as well

                    try:
                                  raise the_instance
                    except Audible:
                                  the_instance.play(largo)
                    except Visual:
                                  the_instance.display(gaudy)
                    except Olfactory:
                                  sniff(the_instance)
                    except:
                                  raise ValueError, "dunno what to do with this!"

This uses the fact that exception catching tests for class or subclass
membership.

A different approach is to test for the presence of a class attribute that
is presumably unique for the given class. For instance:

            class MyClass:
                ThisIsMyClass = 1
                ...

            def is_a_MyClass(the_instance):
                return hasattr(the_instance, 'ThisIsMyClass')

This version is easier to inline, and probably faster (inlined it is
definitely faster). The disadvantage is that someone else could cheat:

            class IntruderClass:
                ThisIsMyClass = 1    # Masquerade as MyClass
                ...

but this may be seen as a feature (anyway, there are plenty of other ways to
cheat in Python). Another disadvantage is that the class must be prepared
for the membership test. If you do not "control the source code" for the
class it may not be advisable to modify the class to support testability.

----------------------------------------------------------------------------

4.48. What is delegation?

Delegation refers to an object oriented technique Python programmers may
implement with particular ease. Consider the following:

      from string import upper

      class UpperOut:
            def __init__(self, outfile):
                  self.__outfile = outfile
            def write(self, str):
                  self.__outfile.write( upper(str) )
            def __getattr__(self, name):
                  return getattr(self.__outfile, name)

Here the UpperOut class redefines the write method to convert the argument
string to upper case before calling the underlying self.__outfile.write
method, but all other methods are delegated to the underlying self.__outfile
object. The delegation is accomplished via the "magic" __getattr__ method.
Please see the language reference for more information on the use of this
method.

Note that for more general cases delegation can get trickier. Particularly
when attributes must be set as well as gotten the class must define a
__settattr__ method too, and it must do so carefully.

The basic implementation of __setattr__ is roughly equivalent to the
following:

       class X:
            ...
            def __setattr__(self, name, value):
                 self.__dict__[name] = value
            ...

Most __setattr__ implementations must modify self.__dict__ to store local
state for self without causing an infinite recursion.

----------------------------------------------------------------------------

4.49. How do I test a Python program or component.

First, it helps to write the program so that it may be easily tested by
using good modular design. In particular your program should have almost all
functionality encapsulated in either functions or class methods -- and this
sometimes has the surprising and delightful effect of making the program run
faster (because local variable accesses are faster than global accesses).
Furthermore the program should avoid depending on mutating global variables,
since this makes testing much more difficult to do.

The "global main logic" of your program may be as simple as

      if __name__=="__main__":
           main_logic()

at the bottom of the main module of your program.

Once your program is organized as a tractible collection of functions and
class behaviours you should write test functions that exercise the
behaviours. A test suite can be associated with each module which automates
a sequence of tests. This sounds like a lot of work, but since Python is so
terse and flexible it's surprisingly easy. You can make coding much more
pleasant and fun by writing your test functions in parallel with the
"production code", since this makes it easy to find bugs and even design
flaws earlier.

"Support modules" that are not intended to be the main module of a program
may include a "test script interpretation" which invokes a self test of the
module.

       if __name__ == "__main__":
          self_test()

Even programs that interact with complex external interfaces may be tested
when the external interfaces are unavailable by using "fake" interfaces
implemented in Python. For an example of a "fake" interface, the following
class defines (part of) a "fake" file interface:

     import string
     testdata = "just a random sequence of characters"

     class FakeInputFile:
       data = testdata
       position = 0
       closed = 0

       def read(self, n=None):
           self.testclosed()
           p = self.position
           if n is None:
              result= self.data[p:]
           else:
              result= self.data[p: p+n]
           self.position = p + len(result)
           return result

       def seek(self, n, m=0):
           self.testclosed()
           last = len(self.data)
           p = self.position
           if m==0:
              final=n
           elif m==1:
              final=n+p
           elif m==2:
              final=len(self.data)+n
           else:
              raise ValueError, "bad m"
           if final<0:
              raise IOError, "negative seek"
           self.position = final

       def isatty(self):
           return 0

       def tell(self):
           return self.position

       def close(self):
           self.closed = 1

       def testclosed(self):
           if self.closed:
              raise IOError, "file closed"

Try f=FakeInputFile() and test out its operations.

----------------------------------------------------------------------------

4.50. My multidimensional list (array) is broken! What gives?

You probably tried to make a multidimensional array like this.

       A = [[None] * 2] * 3

This makes a list containing 3 references to the same list of length two.
Changes to one row will show in all rows, which is probably not what you
want. The following works much better:

       A = [None]*3
       for i in range(3):
            A[i] = [None] * 2

This generates a list containing 3 different lists of length two.

If you feel weird, you can also do it in the following way:

       w, h = 2, 3
       A = map(lambda i,w=w: [None] * w, range(h))

----------------------------------------------------------------------------

4.51. I want to do a complicated sort: can you do a Schwartzian Transform in
Python?

Yes, and in Python you only have to write it once:

     def st(List, Metric):
         def pairing(element, M = Metric):
               return (M(element), element)
         paired = map(pairing, List)
         paired.sort()
         return map(stripit, paired)

     def stripit(pair):
         return pair[1]

This technique, attributed to Randal Schwartz, sorts the elements of a list
by a metric which maps each element to its "sort value". For example, if L
is a list of string then

       import string
       Usorted = st(L, string.upper)

       def intfield(s):
             return string.atoi( string.strip(s[10:15] ) )

       Isorted = st(L, intfield)

Usorted gives the elements of L sorted as if they were upper case, and
Isorted gives the elements of L sorted by the integer values that appear in
the string slices starting at position 10 and ending at position 15. Note
that Isorted may also be computed by

       def Icmp(s1, s2):
             return cmp( intfield(s1), intfield(s2) )

       Isorted = L[:]
       Isorted.sort(Icmp)

but since this method computes intfield many times for each element of L, it
is slower than the Schwartzian Transform.

----------------------------------------------------------------------------

4.52. How to convert between tuples and lists?

The function tuple(seq) converts any sequence into a tuple with the same
items in the same order. For example, tuple([1, 2, 3]) yields (1, 2, 3) and
tuple('abc') yields ('a', 'b', 'c'). If the argument is a tuple, it does not
make a copy but returns the same object, so it is cheap to call tuple() when
you aren't sure that an object is already a tuple.

The function list(seq) converts any sequence into a list with the same items
in the same order. For example, list((1, 2, 3)) yields [1, 2, 3] and
list('abc') yields ['a', 'b', 'c']. If the argument is a list, it makes a
copy just like seq[:] would.

----------------------------------------------------------------------------

4.53. Files retrieved with urllib contain leading garbage that looks like
email headers.

The server is using HTTP/1.1; the vanilla httplib in Python 1.4 only
recognizes HTTP/1.0. See question 4.42 for a patch.

----------------------------------------------------------------------------

4.54. How do I get a list of all instances of a given class?

Python does not keep track of all instances of a class (or of a built-in
type).

You can program the class's constructor to keep track of all instances, but
unless you're very clever, this has the disadvantage that the instances
never get deleted,because your list of all instances keeps a reference to
them.

(The trick is to regularly inspect the reference counts of the instances
you've retained, and if the reference count is below a certain level, remove
it from the list. Determining that level is tricky -- it's definitely larger
than 1.)

----------------------------------------------------------------------------

4.55. A regular expression fails with regex.error: match failure.

This is usually caused by too much backtracking; the regular expression
engine has a fixed size stack which holds at most 4000 backtrack points.
Every character matched by e.g. ".*" accounts for a backtrack point, so even
a simple search like

      regex.match('.*x',"x"*5000)

will fail.

This is fixed in the re module introduced with Python 1.5; consult the
Library Reference section on re for more information.

----------------------------------------------------------------------------

4.56. I can't get signal handlers to work.

The most common problem is that the signal handler is declared with the
wrong argument list. It is called as

            handler(signum, frame)

so it should be declared with two arguments:

            def handler(signum, frame):
                    ...

----------------------------------------------------------------------------

4.57. I can't use a global variable in a function? Help!

Did you do something like this?

       x = 1 # make a global

       def f():
             print x # try to print the global
             ...
             for j in range(100):
                  if q>3:
                     x=4

If you did, all references to x in f are local, not global by virtue of the
"x=4" assignment. Any variable assigned in a function is local to that
function unless it is declared global. Consequently the "print x" attempts
to print an uninitialized local variable and will trigger a NameError.

----------------------------------------------------------------------------

4.58. What's a negative index? Why doesn't list.insert() use them?

Python sequences are indexed with positive numbers and negative numbers. For
positive numbers 0 is the first index 1 is the second index and so forth.
For negative indices -1 is the last index and -2 is the pentultimate (next
to last) index and so forth. Think of seq[-n] as the same as
seq[len(seq)-n].

Using negative indices can be very convenient. For example if the string
Line ends in a newline then Line[:-1] is all of Line except the newline.

Sadly the list builtin method L.insert does not observe negative indices.
This feature could be considered a mistake but since existing programs
depend on this feature it may stay around forever. L.insert for negative
indices inserts at the start of the list. To get "proper" negative index
behaviour use L[n:n] = [x] in place of the insert method.

----------------------------------------------------------------------------

4.59. How can I sort one list by values from another list?

You can sort lists of tuples.

      >>> list1 = ["what", "I'm", "sorting", "by"]
      >>> list2 = ["something", "else", "to", "sort"]
      >>> pairs = map(None, list1, list2)
      >>> pairs
      [('what', 'something'), ("I'm", 'else'), ('sorting', 'to'), ('by', 'sort')]
      >>> pairs.sort()
      >>> pairs
      [("I'm", 'else'), ('by', 'sort'), ('sorting', 'to'), ('what', 'something')]
      >>> result = pairs[:]
      >>> for i in xrange(len(result)): result[i] = result[i][1]
      ...
      >>> result
      ['else', 'sort', 'to', 'something']

And if you didn't understand the question, please see the example above ;c).
Note that "I'm" sorts before "by" because uppercase "I" comes before
lowercase "b" in the ascii order. Also see 4.51.

----------------------------------------------------------------------------

4.60. Why doesn't dir() work on builtin types like files and lists?

It should have -- and it does starting with Python 1.5 (currently in
development -- see Questions 1.13 and 2.10).

Using 1.4, you can find out which methods a given object supports by looking
at its __methods__ attribute:

        >>> List = []
        >>> List.__methods__
        ['append', 'count', 'index', 'insert', 'remove', 'reverse', 'sort']

----------------------------------------------------------------------------

4.61. How can I mimic CGI form submission (METHOD=POST)?

I would like to retrieve web pages that are the result of POSTing a form. Is
there existing code that would let me do this easily?

Yes. Here's a simple example that uses httplib.

        #!/usr/local/bin/python

        import httplib, sys, time

        ### build the query string
        qs = "First=Josephine&MI=Q&Last=Public"

        ### connect and send the server a path
        httpobj = httplib.HTTP('www.some-server.out-there', 80)
        httpobj.putrequest('POST', '/cgi-bin/some-cgi-script')
        ### now generate the rest of the HTTP headers...
        httpobj.putheader('Accept', '*/*')
        httpobj.putheader('Connection', 'Keep-Alive')
        httpobj.putheader('Content-type', 'application/x-www-form-urlencoded')
        httpobj.putheader('Content-length', '%d' % len(qs))
        httpobj.endheaders()
        httpobj.send(qs)
        ### find out what the server said in response...
        reply, msg, hdrs = httpobj.getreply()
        if reply != 200:
            sys.stdout.write(httpobj.getfile().read())

Note that in general for "url encoded posts" (the default) query strings
must be "quoted" to, for example, change equals signs and spaces to an
encoded form when they occur in name or value. Use urllib.quote to perform
this quoting. For example to send name="Guy Steele, Jr.":

       >>> from urllib import quote
       >>> x = quote("Guy Steele, Jr.")
       >>> x
       'Guy%20Steele,%20Jr.'
       >>> query_string = "name="+x
       >>> query_string
       'name=Guy%20Steele,%20Jr.'

----------------------------------------------------------------------------

4.62. If my program crashes with a bsddb (or anydbm) database open, it gets
corrupted. How come?

Databases opened for write access with the bsddb module (and often by the
anydbm module, since it will preferentially use bsddb) must explcitly be
closed using the close method of the database. The underlying libdb package
caches database contents which need to be converted to on-disk form and
written, unlike regular open files which already have the on-disk bits in
the kernel's write buffer, where they can just be dumped by the kernel with
the program exits.

If you have initialized a new bsddb database but not written anything to it
before the program crashes, you will often wind up with a zero-length file
and encounter an exception the next time the file is opened.

----------------------------------------------------------------------------

4.63. How do I make a Python script executable on Unix?

You need to do two things: the script file's mode must be executable
(include the 'x' bit), and the first line must begin with #! followed by the
pathname for the Python interpreter.

The first is done by executing 'chmod +x scriptfile' or perhaps 'chmod 755
scriptfile'.

The second can be done in a number of way. The most straightforward way is
to write

      #!/usr/local/bin/python

as the very first ine of your file - or whatever the pathname is where the
python interpreter is installed on your platform.

If you would like the script to be independent of where the python
interpreter lives, you can use the "env" program. On almost all platforms,
the following woll work, assuming the python interpreter is in a directory
on the user's $PATH:

      #! /usr/bin/env python

Note -- *don't* do this for CGI scripts. The $PATH variable for CGI scripts
is often very minimal, so you need to use the actual absolute pathname of
the interpreter.

Occasionally, a user's environment is so full that the /usr/bin/env program
fails; or there's no env program at all. In that case, you can try the
following hack (due to Alex Rezinsky):

      #! /bin/sh
      """:"
      exec python $0 ${1+"$@"}
      """

The disadvantage is that this defines the script's __doc__ string. However,
you can fix that by adding

      __doc__ = """...Whatever..."""

----------------------------------------------------------------------------

4.64. How do you remove duplicates from a list?

Generally, if you don't mind reordering the List

       if List:
          List.sort()
          last = List[-1]
          for i in range(len(List)-2, -1, -1):
              if last==List[i]: del List[i]
              else: last=List[i]

If all elements of the list may be used as dictionary keys (ie, they are all
hashable) this is often faster

       d = {}
       for x in List: d[x]=x
       List = d.values()

Also, for extremely large lists you might consider more optimal alternatives
to the first one. The second one is pretty good whenever it can be used.

----------------------------------------------------------------------------

4.65. Are there any known year 2000 problems in Python?

I am not aware of year 2000 deficiencies in Python 1.5. Python does very few
date calculations and for what it does, it relies on the C library
functions. Python generally represent times either as seconds since 1970 or
as a tuple (year, month, day, ...) where the year is expressed with four
digits, which makes Y2K bugs unlikely. So as long as your C library is okay,
Python should be okay. Of course, I cannot vouch for your Python code!

Given the nature of freely available software, I have to add that this
statement is not legally binding. The Python copyright notice contains the
following disclaimer:

      STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
      REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
      MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
      CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
      DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
      PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
      TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
      PERFORMANCE OF THIS SOFTWARE.

The good news is that if you encounter a problem, you have full source
available to track it down and fix it!

----------------------------------------------------------------------------

4.66. I want a version of map that applies a method to a sequence of
objects! Help!

Get fancy!

      def method_map(objects, method, arguments):
           """method_map([a,b], "flog", (1,2)) gives [a.flog(1,2), b.flog(1,2)]"""
           nobjects = len(objects)
           methods = map(getattr, objects, [method]*nobjects)
           return map(apply, methods, [arguments]*nobjects)

It's generally a good idea to get to know the mysteries of map and apply and
getattr and the other dynamic features of Python.

----------------------------------------------------------------------------

4.67. How do I generate random numbers in Python?

The standard library module "whrandom" implements a random number generator.
Usage is simple:

        import whrandom

        whrandom.random()

This returns a random floating point number in the range [0, 1).

There are also other specialized generators in this module:

        randint(a, b) chooses an integer in the range [a, b)
        choice(S) chooses from a given sequence
        uniform(a, b) chooses a floating point number in the range [a, b)

To force the random number generator's initial setting, use

        seed(x, y, z) set the seed from three integers in [1, 256)

There's also a class, whrandom, whoch you can instantiate to create
independent multiple random number generators.

The module "random" contains functions that approximate various standard
distributions.

All this is documented in the library reference manual. Note that the module
"rand" is obsolete.

----------------------------------------------------------------------------

4.68. How do I access the serial (RS232) port?

There's a Windows serial communication module (for communication over RS 232
serial ports) at

      http://www.python.org/ftp/python/contrib/System/siomodule.README
      http://www.python.org/ftp/python/contrib/System/siomodule.zip

For DOS, try Hans Nowak's Python-DX, which supports this, at:

      http://www.cuci.nl/~hnowak/

For Unix, search Deja News (using http://www.python.org/search/) for "serial
port" with author Mitch Chapman (his post is a little too long to include
here).

----------------------------------------------------------------------------

4.69. Images on Tk-Buttons don't work in Py15?

They do work, but you must keep your own reference to the image object now.
More verbosely, you must make sure that, say, a global variable or a class
attribute refers to the object.

Quoting Fredrik Lundh from the mailinglist:

      Well, the Tk button widget keeps a reference to the internal
      photoimage object, but Tkinter does not.  So when the last
      Python reference goes away, Tkinter tells Tk to release the
      photoimage.  But since the image is in use by a widget, Tk
      doesn't destroy it.  Not completely.  It just blanks the image,
      making it completely transparent...

      And yes, there was a bug in the keyword argument handling
      in 1.4 that kept an extra reference around in some cases.  And
      when Guido fixed that bug in 1.5, he broke quite a few Tkinter
      programs...

----------------------------------------------------------------------------

4.70. Where is the math.py (socket.py, regex.py, etc.) source file?

If you can't find a source file for a module it may be a builtin or
dynamically loaded module implemented in C, C++ or other compiled language.
In this case you may not have the source file or it may be something like
mathmodule.c, somewhere in a C source directory (not on the Python Path).

Fredrik Lundh (fredrik@pythonware.com) explains (on the python-list):

There are (at least) three kinds of modules in Python: 1) modules written in
Python (.py); 2) modules written in C and dynamically loaded (.dll, .pyd,
.so, .sl, etc); 3) modules written in C and linked with the interpreter; to
get a list of these, type:

        import sys
        print sys.builtin_module_names

----------------------------------------------------------------------------

4.71. How do I send mail from a Python script?

On Unix, it's very simple, using sendmail. The location of the sendmail
program varies between systems; sometimes it is /usr/lib/sendmail, sometime
/usr/sbin/sendmail. The sendmail manual page will help you out. Here's some
sample code:

      SENDMAIL = "/usr/sbin/sendmail" # sendmail location
      import os
      p = os.popen("%s -t" % SENDMAIL, "w")
      p.write("To: cary@ratatosk.org\n")
      p.write("Subject: test\n")
      p.write("\n") # blank line separating headers from body
      p.write("Some text\n")
      p.write("some more text\n")
      sts = p.close()
      if sts != 0:
          print "Sendmail exit status", sts

On non-Unix systems (and on Unix systems too, of course!), you can use SMTP
to send mail to a nearby mail server. A library for SMTP (smtplib.py) is
included in Python 1.5.1; in 1.5.2 it will be documented and extended.
Here's a very simple interactive mail sender that uses it:

        import sys, smtplib

        fromaddr = raw_input("From: ")
        toaddrs  = string.splitfields(raw_input("To: "), ',')
        print "Enter message, end with ^D:"
        msg = ''
        while 1:
            line = sys.stdin.readline()
            if not line:
                break
            msg = msg + line

        # The actual mail send
        server = smtplib.SMTP('localhost')
        server.sendmail(fromaddr, toaddrs, msg)
        server.quit()

This method will work on any host that supports an SMTP listener; otherwise,
you will have to ask the user for a host.

----------------------------------------------------------------------------

4.72. How do I avoid blocking in connect() of a socket?

The select module is widely known to help with asynchronous I/O on sockets
once they are connected. However, it is less than common knowledge how to
avoid blocking on the initial connect() call. Jeremy Hylton has the
following advice (slightly edited):

To prevent the TCP connect from blocking, you can set the socket to
non-blocking mode. Then when you do the connect(), you will either connect
immediately (unlikely) or get an exception that contains the errno.
errno.EINPROGRESS indicates that the connection is in progress, but hasn't
finished yet. Different OSes will return different errnos, so you're going
to have to check. I can tell you that different versions of Solaris return
different errno values.

In Python 1.5 and later, you can use connect_ex() to avoid creating an
exception. It will just return the errno value.

To poll, you can call connect_ex() again later -- 0 or errno.EISCONN
indicate that you're connected -- or you can pass this socket to select
(checking to see if it is writeable).

----------------------------------------------------------------------------

4.73. How do I specify hexadecimal and octal integers?

To specify an octal digit, precede the octal value with a zero. For example,
to set the variable "a" to the octal value "10" (8 in decimal), type:

        >>> a = 010

To verify that this works, you can type "a" and hit enter while in the
interpreter, which will cause Python to spit out the current value of "a" in
decimal:

        >>> a
        8

Hexadecimal is just as easy. Simply precede the hexadecimal number with a
zero, and then a lower or uppercase "x". Hexadecimal digits can be specified
in lower or uppercase. For example, in the Python interpreter:

        >>> a = 0xa5
        >>> a
        165
        >>> b = 0XB2
        >>> b
        178

----------------------------------------------------------------------------

4.74. How to get a single keypress at a time?

For Windows, see question 8.2. Here is an answer for Unix.

There are several solutions; some involve using curses, which is a pretty
big thing to learn. Here's a solution without curses, due to Andrew Kuchling
(adapted from code to do a PGP-style randomness pool):

            import termios, TERMIOS, sys, os
            fd = sys.stdin.fileno()
            old = termios.tcgetattr(fd)
            new = termios.tcgetattr(fd)
            new[3] = new[3] & ~TERMIOS.ICANON & ~TERMIOS.ECHO
            new[6][TERMIOS.VMIN] = 1
            new[6][TERMIOS.VTIME] = 0
            termios.tcsetattr(fd, TERMIOS.TCSANOW, new)
            s = ''    # We'll save the characters typed and add them to the pool.
            try:
                while 1:
                    c = os.read(fd, 1)
                    print "Got character", `c`
                    s = s+c
            finally:
                termios.tcsetattr(fd, TERMIOS.TCSAFLUSH, old)

You need the termios module for any of this to work, and I've only tried it
on Linux, though it should work elsewhere. It turns off stdin's echoing and
disables canonical mode, and then reads a character at a time from stdin,
noting the time after each keystroke.

----------------------------------------------------------------------------

4.75. How can I overload constructors (or methods) in Python?

(This actually applies to all methods, but somehow the question usually
comes up first in the context of constructors.)

Where in C++ you'd write

        class C {
            C() { cout << "No arguments\n"; }
            C(int i) { cout << "Argument is " << i << "\n"; }
        }

in Python you have to write a single constructor that catches all cases
using default arguments. For example:

        class C:
            def __init__(self, i=None):
                if i is None:
                    print "No arguments"
                else:
                    print "Argument is", i

This is not entirely equivalent, but close enough in practice.

You could also try a variable-length argument list, e.g.

            def __init__(self, *args):
                ....

The same approach works for all method definitions.

----------------------------------------------------------------------------

4.76. How do I pass keyword arguments from one method to another?

Use apply. For example:

        class Account:
            def __init__(self, **kw):
                self.accountType = kw.get('accountType')
                self.balance = kw.get('balance')

        class CheckingAccount(Account):
            def __init__(self, **kw):
                kw['accountType'] = 'checking'
                apply(Account.__init__, (self,), kw)

        myAccount = CheckingAccount(balance=100.00)

----------------------------------------------------------------------------

4.77. What module should I use to help with generating HTML?

Check out HTMLgen written by Robin Friedrich. It's a class library of
objects corresponding to all the HTML 3.2 markup tags. It's used when you
are writing in Python and wish to synthesize HTML pages for generating a web
or for CGI forms, etc.

It can be found in the FTP contrib area on python.org or on the Starship.
Use the search engines there to locate the latest version.

It might also be useful to consider DocumentTemplate, which offers clear
separation between Python code and HTML code. DocumentTemplate is part of
the Bobo objects publishing system (http:/www.digicool.com/releases) but can
be used independantly of course!

----------------------------------------------------------------------------

4.78. How do I create documentation from doc strings?

Use gendoc, by Daniel Larson. See

http://starship.skyport.net/crew/danilo/

It can create HTML from the doc strings in your Python source code.

----------------------------------------------------------------------------

4.79. How do I read (or write) binary data?

For complex data formats, it's best to use use the struct module. It's
documented in the library reference. It allows you to take a string read
from a file containing binary data (usually numbers) and convert it to
Python objects; and vice versa.

For example, the following code reads two 2-byte integers and one 4-byte
integer in big-endian format from a file:

      import struct

      f = open(filename, "rb")  # Open in binary mode for portability
      s = f.read(8)
      x, y, z = struct.unpack(">hhl", s)

The '>' in the format string forces bin-endian data; the letter 'h' reads
one "short integer" (2 bytes), and 'l' reads one "long integer" (4 bytes)
from the string.

For data that is more regular (e.g. a homogeneous list of ints or floats),
you can also use the array module, also documented in the library reference.

----------------------------------------------------------------------------

4.80. I can't get key bindings to work in Tkinter

An oft-heard complaint is that event handlers bound to events with the
bind() method don't get handled even when the appropriate key is pressed.

The most common cause is that the widget to which the binding applies
doesn't have "keyboard focus". Check out the Tk documentation for the focus
command. Usually a widget is given the keyboard focus by clicking in it (but
not for labels; see the taketocus option).

----------------------------------------------------------------------------

4.81. "import crypt" fails

[Unix]

Starting with Python 1.5, the crypt module is disabled by default. In order
to enable it, you must go into the Python source tree and edit the file
Modules/Setup to enable it (remove a '#' sign in front of the line starting
with '#crypt'). Then rebuild. You may also have to add the string '-lcrypt'
to that same line.

----------------------------------------------------------------------------

4.82. Are there coding standards or a style guide for Python programs?

Yes, Guido has written the "Python Style Guide". See
http://www.python.org/doc/essays/styleguide.html

----------------------------------------------------------------------------

4.83. How do I freeze Tkinter applications?

Freeze is a tool to create stand-alone applications (see 4.28).

When freezing Tkinter applications, the applications will not be truly
stand-alone, as the application will still need the tcl and tk libraries.

One solution is to ship the application with the tcl and tk libraries, and
point to them at run-time using the TCL_LIBRARY and TK_LIBRARY environment
variables.

To get truly stand-alone applications, the Tcl scripts that form the library
have to be integrated into the application as well. One tool supporting that
is SAM (stand-alone modules), which is part of the Tix distribution
(http://tix.mne.com). Build Tix with SAM enabled, perform the appropriate
call to Tclsam_init etc inside Python's Modules/tkappinit.c, and link with
libtclsam and libtksam (you might include the Tix libraries as well).

----------------------------------------------------------------------------

4.84. How do I create static class data and static class methods?

[Tim Peters, tim_one@email.msn.com]

Static data (in the sense of C++ or Java) is easy; static methods (again in
the sense of C++ or Java) are not supported directly.

STATIC DATA

For example,

        class C:
            count = 0   # number of times C.__init__ called

            def __init__(self):
                C.count = C.count + 1

            def getcount(self):
                return C.count  # or return self.count

c.count also refers to C.count for any c such that isinstance(c, C) holds,
unless overridden by c itself or by some class on the base-class search path
from c.__class__ back to C.

Caution: within a method of C,

        self.count = 42

creates a new and unrelated instance vrbl named "count" in self's own dict.
So rebinding of a class-static data name needs the

        C.count = 314

form whether inside a method or not.

STATIC METHODS

Static methods (as opposed to static data) are unnatural in Python, because

        C.getcount

returns an unbound method object, which can't be invoked without supplying
an instance of C as the first argument.

The intended way to get the effect of a static method is via a module-level
function:

        def getcount():
            return C.count

If your code is structured so as to define one class (or tightly related
class hierarchy) per module, this supplies the desired encapsulation.

Several tortured schemes for faking static methods can be found by searching
DejaNews. Most people feel such cures are worse than the disease. Perhaps
the least obnoxious is due to Pekka Pessi (mailto:ppessi@hut.fi):

        # helper class to disguise function objects
        class _static:
            def __init__(self, f):
                self.__call__ = f

        class C:
            count = 0

            def __init__(self):
                C.count = C.count + 1

            def getcount():
                return C.count
            getcount = _static(getcount)

            def sum(x, y):
                return x + y
            sum = _static(sum)

        C(); C()
        c = C()
        print C.getcount()  # prints 3
        print c.getcount()  # prints 3
        print C.sum(27, 15) # prints 42

----------------------------------------------------------------------------

4.85. __import__('x.y.z') returns <module 'x'>; how do I get z?

Try

       __import__('x.y.z').y.z

For more realistic situations, you may have to do something like

       m = __import__(s)
       for i in string.split(s, ".")[1:]:
           m = getattr(m, i)

----------------------------------------------------------------------------

4.86. Basic thread wisdom

If you write a simple test program like this:

      import thread
      def run(name, n):
          for i in range(n): print name, i
      for i in range(10):
          thread.start_new(run, (i, 100))

none of the threads seem to run! The reason is that as soon as the main
thread exits, all threads are killed.

A simple fix is to add a sleep to the end of the program, sufficiently long
for all threads to finish:

      import thread, time
      def run(name, n):
          for i in range(n): print name, i
      for i in range(10):
          thread.start_new(run, (i, 100))
      time.sleep(10) # <----------------------------!

But now (on many platforms) the threads don't run in parallel, but appear to
run sequentially, one at a time! The reason is that the OS thread scheduler
doesn't start a new thread until the previous thread is blocked.

A simple fix is to add a tiny sleep to the start of the run function:

      import thread, time
      def run(name, n):
          time.sleep(0.001) # <---------------------!
          for i in range(n): print name, i
      for i in range(10):
          thread.start_new(run, (i, 100))
      time.sleep(10)

Some more hints:

Instead of using a time.sleep() call at the end, it's better to use some
kind of semaphore mechanism. One idea is to use a the Queue module to create
a queue object, let each thread append a token to the queue when it
finishes, and let the main thread read as many tokens from the queue as
there are threads.

Use the threading module instead of the thread module. It's part of Python
since version 1.5.1. It takes care of all these details, and has many other
nice features too!

----------------------------------------------------------------------------

4.87. Why doesn't closing sys.stdout (stdin, stderr) really close it?

Python file objects are a high-level layer of abstraction on top of C
streams, which in turn are a medium-level layer of abstraction on top of
(among other things) low-level C file descriptors.

For most file objects f you create in Python via the builtin "open"
function, f.close() marks the Python file object as being closed from
Python's point of view, and also arranges to close the underlying C stream.
This happens automatically too, in f's destructor, when f becomes garbage.

But stdin, stdout and stderr are treated specially by Python, because of the
special status also given to them by C: doing

        sys.stdout.close() # ditto for stdin and stderr

marks the Python-level file object as being closed, but does not close the
associated C stream (provided sys.stdout is still bound to its default
value, which is the stream C also calls "stdout").

To close the underlying C stream for one of these three, you should first be
sure that's what you really want to do (e.g., you may confuse the heck out
of extension modules trying to do I/O). If it is, use os.close:

        os.close(0)   # close C's stdin stream
        os.close(1)   # close C's stdout stream
        os.close(2)   # close C's stderr stream

----------------------------------------------------------------------------

4.88. What kinds of global value mutation are thread-safe?

[adapted from c.l.py responses by Gordon McMillan & GvR]

A global interpreter lock is used internally to ensure that only one thread
runs in the Python VM at a time. In general, Python offers to switch among
threads only between bytecode instructions (how frequently it offers to
switch can be set via sys.setcheckinterval). Each bytecode instruction-- and
all the C implementation code reached from it --is therefore atomic.

In theory, this means an exact accounting requires an exact understanding of
the PVM bytecode implementation. In practice, it means that operations on
shared vrbls of builtin data types (ints, lists, dicts, etc) that "look
atomic" really are.

For example, these are atomic (L, L1, L2 are lists, D, D1, D2 are dicts, x,
y are objects, i, j are ints):

        L.append(x)
        L1.extend(L2)
        x = L[i]
        x = L.pop()
        L1[i:j] = L2
        L.sort()
        x = y
        x.field = y
        D[x] = y
        D1.update(D2)
        D.keys()

These aren't:

        i = i+1
        L.append(L[-1])
        L[i] = L[j]
        D[x] = D[x] + 1

Note: operations that replace other objects may invoke those other objects'
__del__ method when their reference count reaches zero, and that can affect
things. This is especially true for the mass updates to dictionaries and
lists. When in doubt, use a mutex!

----------------------------------------------------------------------------

4.89. How do I modify a string in place?

Strings are immutable (see question 6.2) so you cannot modify a string
directly. If you need an object with this ability, try converting the string
to a list or take a look at the array module.

        >>> s = "Hello, world"
        >>> a = list(s)
        >>> print a
        ['H', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd']
        >>> a[7:] = list("there!")
        >>> import string
        >>> print string.join(a, '')
        'Hello, there!'

        >>> import array
        >>> a = array.array('c', s)
        >>> print a
        array('c', 'Hello, world')
        >>> a[0] = 'y' ; print a
        array('c', 'yello world')
        >>> a.tostring()
        'yello, world'

----------------------------------------------------------------------------

4.90. How to pass on keyword/optional parameters/arguments

Q: How can I pass on optional or keyword parameters from one function

       to another?

A: Use 'apply', like:

            def f1(a, *b, **c):
                    ...

            def f2(x, *y, **z):
                    ...
                    z['width']='14.3c'
                    ...
                    apply(f1, (a,)+b, c)

----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:59 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:59 GMT
Subject: Python Language FAQ - Section 8
Message-ID: <mt2.0-6734-931390079@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 8

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

8. Python on Windows

8.1.  Using Python for CGI on Microsoft Windows
8.2.  How to check for a keypress without blocking?
8.3.  $PYTHONPATH
8.4.  dedent syntax errors
8.5.  How do I emulate os.kill() in Windows?
8.6.  Why does os.path.isdir() fail on NT shared directories?
8.7.  PyRun_SimpleFile() crashes on Windows but not on Unix
8.8.  Import of _tkinter fails on Windows 95/98
8.9.  Can't extract the downloaded documentation on Windows
8.10. Can't get Py_RunSimpleFile() to work.
8.11. Where is Freeze for Windows?
8.12. Is a *.pyd file the same as a DLL?
8.13. Missing cw3215mt.dll (or missing cw3215.dll)

----------------------------------------------------------------------------

8. Python on Windows

----------------------------------------------------------------------------

8.1. Using Python for CGI on Microsoft Windows

Setting up the Microsoft IIS Server/Peer Server:

On the Microsoft IIS server or on the Win95 MS Personal Web Server you set
up python in the same way that you would set up any other scripting engine.

Run regedt32 and go to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\ScriptMap

and enter the following line (making any specific changes that your system
may need)

.py :REG_SZ: c:\<path to python>\python.exe -u %s %s

This line will allow you to call your script with a simple reference like:
http://yourserver/scripts/yourscript.py provided "scripts" is an
"executable" directory for your server (which it usually is by default). The
"-u" flag specifies unbuffered and binary mode for stdin - needed when
working with binary data

In addition, it is recommended by people who would know that using ".py" may
not be a good idea for the file extensions when used in this context (you
might want to reserve *.py for support modules and use *.cgi or *.cgp for
"main program" scripts). However, that issue is beyond this Windows FAQ
entry.

Netscape Servers: Information on this topic exists at:
http://home.netscape.com/comprod/server_central/support/fasttrack_man/programs.htm#1010870

----------------------------------------------------------------------------

8.2. How to check for a keypress without blocking?

Use the msvcrt module. This is a standard Windows-specific extensions in
Python 1.5 and beyond. It defines a function kbhit() which checks whether a
keyboard hit is present; also getch() which gets one character without echo.
Plus a few other goodies.

(Search for "keypress" to find an answer for Unix as well.)

----------------------------------------------------------------------------

8.3. $PYTHONPATH

In MS-DOS derived environments, a unix variable such as $PYTHONPATH is set
as PYTHONPATH, without the dollar sign. PYTHONPATH is useful for specifying
the location of library files.

----------------------------------------------------------------------------

8.4. dedent syntax errors

Tim <tim_one@email.msn.com> sez: the original content of this FAQ (below)
makes little sense. The FAQ does not recommend using tabs, and Guido's
Python Style Guide recommends 4 spaces for distributed Python code; this is
also the Emacs python-mode default; see

        http://www.python.org/doc/essays/styleguide.html

Under any editor mixing tabs and spaces is a bad idea. MSVC is no different
in this respect, and is easily configured to use spaces: Take Tools ->
Options -> Tabs, and for file type "Default" set "Tab size" and "Indent
size" to 4, and select the "Insert spaces" radio button.

If you suspect mixed tabs and spaces are causing problems in leading
whitespace, run Python with the -t switch or, run Tools/Scripts/tabnanny.py
to check a directory tree in batch mode.

[original follows]

The FAQ really means it when it suggests using tabs, not spaces, for
indentation control. This may be a bigger problem in windows than in unix.
For instance, the Microsoft Visual C++ programmers editor, in its default
configuration, does not indicate whether the white space is spaces or tabs.
If it is spaces, you are likely to get syntax errors not obviously related
to the indentation.

----------------------------------------------------------------------------

8.5. How do I emulate os.kill() in Windows?

Use win32api:

        def kill(pid):
            """kill function for Win32"""
            import win32api
            handle = win32api.OpenProcess(1, 0, pid)
            return (0 != win32api.TerminateProcess(handle, 0))

----------------------------------------------------------------------------

8.6. Why does os.path.isdir() fail on NT shared directories?

The solution appears to be always append the "\\" on the end of shared
drives.

      >>> import os
      >>> os.path.isdir( '\\\\rorschach\\public')
      0
      >>> os.path.isdir( '\\\\rorschach\\public\\')
      1

[Blake Winton responds:] I've had the same problem doing "Start >> Run" and
then a directory on a shared drive. If I use "\\rorschach\public", it will
fail, but if I use "\\rorschach\public\", it will work. For that matter,
os.stat() does the same thing (well, it gives an error for
"\\\\rorschach\\public", but you get the idea)...

I've got a theory about why this happens, but it's only a theory. NT knows
the difference between shared directories, and regular directories.
"\\rorschach\public" isn't a directory, it's _really_ an IPC abstraction.
This is sort of lended credence to by the fact that when you're mapping a
network drive, you can't map "\\rorschach\public\utils", but only
"\\rorschach\public".

[Clarification by funkster@midwinter.com] It's not actually a Python
question, as Python is working just fine; it's clearing up something a bit
muddled about Windows networked drives.

It helps to think of share points as being like drive letters. Example:

            k: is not a directory
            k:\ is a directory
            k:\media is a directory
            k:\media\ is not a directory

The same rules apply if you substitute "k:" with "\\conky\foo":

            \\conky\foo  is not a directory
            \\conky\foo\ is a directory
            \\conky\foo\media is a directory
            \\conky\foo\media\ is not a directory

----------------------------------------------------------------------------

8.7. PyRun_SimpleFile() crashes on Windows but not on Unix

I've seen a number of reports of PyRun_SimpleFile() failing in a Windows
port of an application embedding Python that worked fine on Unix.
PyRun_SimpleString() works fine on both platforms.

I think this happens because the application was compiled with a different
set of compiler flags than Python15.DLL. It seems that some compiler flags
affect the standard I/O library in such a way that using different flags
makes calls fail. You need to set it for multi-threaded DLL.

----------------------------------------------------------------------------

8.8. Import of _tkinter fails on Windows 95/98

Sometimes, the import of _tkinter fails on Windows 95 or 98, complaining
with a message like the following:

      ImportError: DLL load failed: One of the library files needed
      to run this application cannot be found.

It could be that you haven't installed Tcl/Tk, but if you did install
Tcl/Tk, and the Wish application works correctly, the problem may be that
its installer didn't manage to edit the autoexec.bat file correctly. It
tries to add a statement that changes the PATH environment variable to
include the Tcl/Tk 'bin' subdirectory, but sometimes this edit doesn't quite
work. Opening it with notepad usually reveals what the problem is.

(One additional hint, noted by David Szafranski: you can't use long
filenames here; e.g. use C:\PROGRA~1\Tcl\bin instead of C:\Program
Files\Tcl\bin.)

----------------------------------------------------------------------------

8.9. Can't extract the downloaded documentation on Windows

Sometimes, when you download the documentation package to a Windows machine
using a web browser, the file extension of the saved file ends up being
.EXE. This is a mistake; the extension should be .TGZ.

Simply rename the downloaded file to have the .TGZ extension, and WinZip
will be able to handle it. (If your copy of WinZip doesn't, get a newer one
from http://www.winzip.com.)

----------------------------------------------------------------------------

8.10. Can't get Py_RunSimpleFile() to work.

This is very sensitive to the compiler vendor, version and (perhaps) even
options. If the FILE* structure in your embedding program isn't the same as
is assumed by the Python interpreter it won't work.

The Python 1.5.* DLLs (python15.dll) are all compiled with MS VC++ 5.0 and
with multithreading-DLL options (/MD, I think).

If you can't change compilers or flags, try using Py_RunSimpleString(). A
trick to get it to run an arbitrary file is to construct a call to
execfile() with the name of your file as argument.

----------------------------------------------------------------------------

8.11. Where is Freeze for Windows?

("Freeze" is a program that allows you to ship a Python program as a single
stand-alone executable file. It is not a compiler, your programs don't run
any faster, but they are more easily distributable (to platforms with the
same OS and CPU). Read the README file of the freeze program for more
disclaimers.)

You can use freeze on Windows, but you must download the source tree (see
http://www.python.org/download/download_source.html). This is recommended
for Python 1.5.2 (and betas thereof) only; older versions don't quite work.

You need the Microsoft VC++ 5.0 compiler (maybe it works with 6.0 too). You
probably need to build Python -- the project files are all in the PCbuild
directory.

The freeze program is in the Tools\freeze subdirectory of the source tree.

----------------------------------------------------------------------------

8.12. Is a *.pyd file the same as a DLL?

Yes, .pyd files are dll's. But there are a few differences. If you have a
DLL named foo.pyd, then it must have a function initfoo(). You can then
write Python "import foo", and Python will search for foo.pyd (as well as
foo.py, foo.pyc) and if it finds it, will attempt to call initfoo() to
initialize it. You do not link your .exe with foo.lib, as that would cause
Windows to require the DLL to be present.

Note that the search path for foo.pyc is PYTHONPATH, not the same as the
path that Windows uses to search for foo.dll. Also, foo.pyd need not be
present to run your program, whereas if you linked your program with a dll,
the dll is required. Of course, foo.pyd is required if you want to say
"import foo". In a dll, linkage is declared in the source code with
__declspec(dllexport). In a .pyd, linkage is defined in a list of available
functions.

----------------------------------------------------------------------------

8.13. Missing cw3215mt.dll (or missing cw3215.dll)

Sometimes, when using Tkinter on Windows, you get an error that cw3215mt.dll
or cw3215.dll is missing.

Cause: you have an old Tcl/Tk DLL built with cygwin in your path (probably
C:\Windows). You must use the Tcl/Tk DLLs from the standard Tcl/Tk
installation (Python 1.5.2 comes with one).


----------------------------------------------------------------------------

-- 
----------- comp.lang.python.announce (moderated) ----------
Article Submission Address:  python-announce@python.org
Python Language Home Page:   http://www.python.org/
Python Quick Help Index:     http://www.python.org/Help.html
------------------------------------------------------------


From python-announce@python.org  Thu Jul  8 00:27:52 1999
From: python-announce@python.org (Markus Fleck)
Date: Wed, 07 Jul 99 23:27:52 GMT
Subject: Python Language FAQ - Section 6
Message-ID: <mt2.0-6734-931390072@news.informatik.uni-bonn.de>

This FAQ newsgroup posting has been automatically converted from an
HTML snapshot of the original Python FAQ; please refer to the original
"Python FAQ Wizard" at <http://grail.cnri.reston.va.us/cgi-bin/faqw.py>
if source code snippets given in this document do not work - incidentally
some formatting information may have been lost during the conversion.

----------------------------------------------------------------------------

The whole Python FAQ - Section 6

Last changed on Mon Jun 28 19:36:09 1999 EDT

(Entries marked with ** were changed within the last 24 hours; entries
marked with * were changed within the last 7 days.)

----------------------------------------------------------------------------

6. Python's design

6.1.  Why isn't there a switch or case statement in Python?
6.2.  Why does Python use indentation for grouping of statements?
6.3.  Why are Python strings immutable?
6.4.  Why don't strings have methods like index() or sort(), like lists?
6.5.  Why does Python use methods for some functionality (e.g.
      list.index()) but functions for other (e.g. len(list))?
6.6.  Why can't I derive a class from built-in types (e.g. lists or
      files)?
6.7.  Why must 'self' be declared and used explicitly in method
      definitions and calls?
6.8.  Can't you emulate threads in the interpreter instead of relying on
      an OS-specific thread implementation?
6.9.  Why can't lambda forms contain statements?
6.10. Why don't lambdas have access to variables defined in the
      containing scope?
6.11. Why can't recursive functions be defined inside other functions?
6.12. Why is there no more efficient way of iterating over a dictionary
      than first constructing the list of keys()?
6.13. Can Python be compiled to machine code, C or some other language?
6.14. How does Python manage memory? Why not full garbage collection?
6.15. Why are there separate tuple and list data types?
6.16. How are lists implemented?
6.17. How are dictionaries implemented?
6.18. Why must dictionary keys be immutable?
6.19. How the heck do you make an array in Python?
6.20. Why doesn't list.sort() return the sorted list?
6.21. How do you specify and enforce an interface spec in Python?
6.22. Why do all classes have the same type? Why do instances all have
      the same type?
6.23. Why isn't all memory freed when Python exits?
6.24. Why no class methods or mutable class variables?
6.25. Why are default values sometimes shared between objects?
6.26. Why no goto?
6.27. How do you make a higher order function in Python?
6.28. Why do I get a SyntaxError for a 'continue' inside a 'try'?
6.29. Why can't raw strings (r-strings) end with a backslash?
6.30. Why can't I use an assignment in an expression?

----------------------------------------------------------------------------

6. Python's design

----------------------------------------------------------------------------

6.1. Why isn't there a switch or case statement in Python?

You can do this easily enough with a sequence of if... elif... elif... else.
There have been some proposals for switch statement syntax, but there is no
consensus (yet) on whether and how to do range tests.

----------------------------------------------------------------------------

6.2. Why does Python use indentation for grouping of statements?

Basically I believe that using indentation for grouping is extremely elegant
and contributes a lot to the clarity of the average Python program. Most
people learn to love this feature after a while. Some arguments for it:

Since there are no begin/end brackets there cannot be a disagreement between
grouping perceived by the parser and the human reader. I remember long ago
seeing a C fragment like this:

            if (x <= y)
                    x++;
                    y--;
            z++;

and staring a long time at it wondering why y was being decremented even for
x > y... (And I wasn't a C newbie then either.)

Since there are no begin/end brackets, Python is much less prone to
coding-style conflicts. In C there are loads of different ways to place the
braces (including the choice whether to place braces around single
statements in certain cases, for consistency). If you're used to reading
(and writing) code that uses one style, you will feel at least slightly
uneasy when reading (or being required to write) another style. Many coding
styles place begin/end brackets on a line by themself. This makes programs
considerably longer and wastes valuable screen space, making it harder to
get a good overview over a program. Ideally, a function should fit on one
basic tty screen (say, 20 lines). 20 lines of Python are worth a LOT more
than 20 lines of C. This is not solely due to the lack of begin/end brackets
(the lack of declarations also helps, and the powerful operations of
course), but it certainly helps!

----------------------------------------------------------------------------

6.3. Why are Python strings immutable?

There are two advantages. One is performance: knowing that a string is
immutable makes it easy to lay it out at construction time -- fixed and
unchanging storage requirements. (This is also one of the reasons for the
distinction between tuples and lists.) The other is that strings in Python
are considered as "elemental" as numbers. No amount of activity will change
the value 8 to anything else, and in Python, no amount of activity will
change the string "eight" to anything else. (Adapted from Jim Roskind)

----------------------------------------------------------------------------

6.4. Why don't strings have methods like index() or sort(), like lists?

Good question. Strings currently don't have methods at all (likewise tuples
and numbers). Long ago, it seemed unnecessary to implement any of these
functions in C, so a standard library module "string" written in Python was
created that performs string related operations. Since then, the cry for
performance has moved most of them into the built-in module strop (this is
imported by module string, which is still the preferred interface, without
loss of performance except during initialization). Some of these functions
(e.g. index()) could easily be implemented as string methods instead, but
others (e.g. sort()) can't, since their interface prescribes that they
modify the object, while strings are immutable (see the previous question).

----------------------------------------------------------------------------

6.5. Why does Python use methods for some functionality (e.g. list.index())
but functions for other (e.g. len(list))?

Functions are used for those operations that are generic for a group of
types and which should work even for objects that don't have methods at all
(e.g. numbers, strings, tuples). Also, implementing len(), max(), min() as a
built-in function is actually less code than implementing them as methods
for each type. One can quibble about individual cases but it's really too
late to change such things fundamentally now.

----------------------------------------------------------------------------

6.6. Why can't I derive a class from built-in types (e.g. lists or files)?

This is caused by the relatively late addition of (user-defined) classes to
the language -- the implementation framework doesn't easily allow it. See
the answer to question 4.2 for a work-around. This may be fixed in the
(distant) future.

----------------------------------------------------------------------------

6.7. Why must 'self' be declared and used explicitly in method definitions
and calls?

By asking this question you reveal your C++ background. :-) When I added
classes, this was (again) the simplest way of implementing methods without
too many changes to the interpreter. I borrowed the idea from Modula-3. It
turns out to be very useful, for a variety of reasons.

First, it makes it more obvious that you are using a method or instance
attribute instead of a local variable. Reading "self.x" or "self.meth()"
makes it absolutely clear that an instance variable or method is used even
if you don't know the class definition by heart. In C++, you can sort of
tell by the lack of a local variable declaration (assuming globals are rare
or easily recognizable) -- but in Python, there are no local variable
declarations, so you'd have to look up the class definition to be sure.

Second, it means that no special syntax is necessary if you want to
explicitly reference or call the method from a particular class. In C++, if
you want to use a method from base class that is overridden in a derived
class, you have to use the :: operator -- in Python you can write
baseclass.methodname(self, <argument list>). This is particularly useful for
__init__() methods, and in general in cases where a derived class method
wants to extend the base class method of the same name and thus has to call
the base class method somehow.

Lastly, for instance variables, it solves a syntactic problem with
assignment: since local variables in Python are (by definition!) those
variables to which a value assigned in a function body (and that aren't
explicitly declared global), there has to be some way to tell the
interpreter that an assignment was meant to assign to an instance variable
instead of to a local variable, and it should preferably be syntactic (for
efficiency reasons). C++ does this through declarations, but Python doesn't
have declarations and it would be a pity having to introduce them just for
this purpose. Using the explicit "self.var" solves this nicely. Similarly,
for using instance variables, having to write "self.var" means that
references to unqualified names inside a method don't have to search the
instance's directories.

----------------------------------------------------------------------------

6.8. Can't you emulate threads in the interpreter instead of relying on an
OS-specific thread implementation?

Unfortunately, the interpreter pushes at least one C stack frame for each
Python stack frame. Also, extensions can call back into Python at almost
random moments. Therefore a complete threads implementation requires thread
support for C.

----------------------------------------------------------------------------

6.9. Why can't lambda forms contain statements?

Python lambda forms cannot contain statements because Python's syntactic
framework can't handle statements nested inside expressions.

However, in Python, this is not a serious problem. Unlike lambda forms in
other languages, where they add functionality, Python lambdas are only a
shorthand notation if you're too lazy to define a function.

Functions are already first class objects in Python, and can be declared in
a local scope. Therefore the only advantage of using a lambda form instead
of a locally-defined function is that you don't need to invent a name for
the function -- but that's just a local variable to which the function
object (which is exactly the same type of object that a lambda form yields)
is assigned!

----------------------------------------------------------------------------

6.10. Why don't lambdas have access to variables defined in the containing
scope?

Because they are implemented as ordinary functions. See question 4.5 above.

----------------------------------------------------------------------------

6.11. Why can't recursive functions be defined inside other functions?

See question 4.5 above. But actually recursive functions can be defined in
other functions with some trickery.

        def test():
            class factorial:
                 def __call__(self, n):
                     if n<=1: return 1
                     return n * self(n-1)
            return factorial()

        fact = test()

The instance created by factorial() above acts like the recursive factorial
function.

Mutually recursive functions can be passed to each other as arguments.

----------------------------------------------------------------------------

6.12. Why is there no more efficient way of iterating over a dictionary than
first constructing the list of keys()?

Have you tried it? I bet it's fast enough for your purposes! In most cases
such a list takes only a few percent of the space occupied by the
dictionary. Apart from the fixed header, the list needs only 4 bytes (the
size of a pointer) per key. A dictionary uses 12 bytes per key plus between
30 and 70 percent hash table overhead, plus the space for the keys and
values. By necessity, all keys are distinct objects, and a string object
(the most common key type) costs at least 20 bytes plus the length of the
string. Add to that the values contained in the dictionary, and you see that
4 bytes more per item really isn't that much more memory...

A call to dict.keys() makes one fast scan over the dictionary (internally,
the iteration function does exist) copying the pointers to the key objects
into a pre-allocated list object of the right size. The iteration time isn't
lost (since you'll have to iterate anyway -- unless in the majority of cases
your loop terminates very prematurely (which I doubt since you're getting
the keys in random order).

I don't expose the dictionary iteration operation to Python programmers
because the dictionary shouldn't be modified during the entire iteration --
if it is, there's a small chance that the dictionary is reorganized because
the hash table becomes too full, and then the iteration may miss some items
and see others twice. Exactly because this only occurs rarely, it would lead
to hidden bugs in programs: it's easy never to have it happen during test
runs if you only insert or delete a few items per iteration -- but your
users will surely hit upon it sooner or later.

----------------------------------------------------------------------------

6.13. Can Python be compiled to machine code, C or some other language?

Not easily. Python's high level data types, dynamic typing of objects and
run-time invocation of the interpreter (using eval() or exec) together mean
that a "compiled" Python program would probably consist mostly of calls into
the Python run-time system, even for seemingly simple operations like "x+1".
Thus, the performance gain would probably be minimal.

Internally, Python source code is always translated into a "virtual machine
code" or "byte code" representation before it is interpreted (by the "Python
virtual machine" or "bytecode interpreter"). In order to avoid the overhead
of parsing and translating modules that rarely change over and over again,
this byte code is written on a file whose name ends in ".pyc" whenever a
module is parsed (from a file whose name ends in ".py"). When the
corresponding .py file is changed, it is parsed and translated again and the
.pyc file is rewritten.

There is no performance difference once the .pyc file has been loaded (the
bytecode read from the .pyc file is exactly the same as the bytecode created
by direct translation). The only difference is that loading code from a .pyc
file is faster than parsing and translating a .py file, so the presence of
precompiled .pyc files will generally improve start-up time of Python
scripts. If desired, the Lib/compileall.py module/script can be used to
force creation of valid .pyc files for a given set of modules.

Note that the main script executed by Python, even if its filename ends in
.py, is not compiled to a .pyc file. It is compiled to bytecode, but the
bytecode is not saved to a file.

If you are looking for a way to translate Python programs in order to
distribute them in binary form, without the need to distribute the
interpreter and library as well, have a look at the freeze.py script in the
Tools/freeze directory. This creates a single binary file incorporating your
program, the Python interpreter, and those parts of the Python library that
are needed by your program. Of course, the resulting binary will only run on
the same type of platform as that used to create it.

----------------------------------------------------------------------------

6.14. How does Python manage memory? Why not full garbage collection?

The details of Python memory management depend on the implementation. The
standard Python implementation (the C implementation) uses reference
counting memory management. This means that when an object is no longer in
use Python frees the object automatically, with a few exceptions.

On the other hand, JPython relies on the Java runtime; so it uses the JVM's
garbage collector. This difference can cause some subtle porting problems if
your Python code depends on the behavior of the reference counting
implementation.

Two exceptions to bear in mind for standard Python are:

1) if the object lies on a circular reference path it won't be freed unless
the circularities are broken. EG:

           List = [None]
           List[0] = List

List will not be freed unless the circularity (List[0] is List) is broken.
The reason List will not be freed is because although it may become
inaccessible the list contains a reference to itself, and reference counting
only deallocates an object when all references to an object are destroyed.
To break the circular reference path we must destroy the reference, as in

           List[0] = None

So, if your program creates circular references (and if it is long running
and/or consumes lots of memory) it may have to do some explicit management
of circular structures. In many application domains this is needed rarely,
if ever.

2) Sometimes objects get stuck in "tracebacks" temporarily and hence are not
deallocated when you might expect. Clear the tracebacks via

           import sys
           sys.exc_traceback = sys.last_traceback = None

Tracebacks are used for reporting errors and implementing debuggers and
related things. They contain a portion of the program state extracted during
the handling of an exception (usually the most recent exception).

In the absence of circularities and modulo tracebacks, Python programs need
not explicitly manage memory.

It is often suggested that Python could benefit from fully general garbage
collection. It's looking less and less likely that Python will ever get
"automatic" garbage collection (GC). For one thing, unless this were added
to C as a standard feature, it's a portability pain in the ass. And yes, I
know about the Xerox library. It has bits of assembler code for most common
platforms. Not for all. And although it is mostly transparent, it isn't
completely transparent (when I once linked Python with it, it dumped core).

"Proper" GC also becomes a problem when Python gets embedded into other
applications. While in a stand-alone Python it may be fine to replace the
standard malloc() and free() with versions provided by the GC library, an
application embedding Python may want to have its own substitute for
malloc() and free(), and may not want Python's. Right now, Python works with
anything that implements malloc() and free() properly.

In JPython, which has garbage collection, the following code (which is fine
in C Python) will probably run out of file descriptors long before it runs
out of memory:

            for file in <very long list of files>:
                    f = open(file)
                    c = f.read(1)

Using the current reference counting and destructor scheme, each new
assignment to f closes the previous file. Using GC, this is not guaranteed.
Sure, you can think of ways to fix this. But it's not off-the-shelf
technology. If you want to write code that will work with any Python
implementation, you should explicitly close the file; this will work
regardless of GC:

           for file in <very long list of files>:
                    f = open(file)
                    c = f.read(1)
                    f.close()

All that said, somebody has managed to add GC to Python using the GC library
fromn Xerox, so you can see for yourself. See

            http://starship.python.net/crew/gandalf/gc-ss.html

See also question 4.17 for ways to plug some common memory leaks manually.

If you're not satisfied with the answers here, before you post to the
newsgroup, please read this summary of past discussions on GC for Python by
Moshe Zadka:

            http://www.geocities.com/TheTropics/Island/2932/gcpy.html

----------------------------------------------------------------------------

6.15. Why are there separate tuple and list data types?

This is done so that tuples can be immutable while lists are mutable.

Immutable tuples are useful in situations where you need to pass a few items
to a function and don't want the function to modify the tuple; for example,

            point1 = (120, 140)
            point2 = (200, 300)
            record(point1, point2)
            draw(point1, point2)

You don't want to have to think about what would happen if record() changed
the coordinates -- it can't, because the tuples are immutable.

On the other hand, when creating large lists dynamically, it is absolutely
crucial that they are mutable -- adding elements to a tuple one by one
requires using the concatenation operator, which makes it quadratic in time.

As a general guideline, use tuples like you would use structs in C or
records in Pascal, use lists like (variable length) arrays.

----------------------------------------------------------------------------

6.16. How are lists implemented?

Despite what a Lisper might think, Python's lists are really variable-length
arrays. The implementation uses a contiguous array of references to other
objects, and keeps a pointer to this array (as well as its length) in a list
head structure.

This makes indexing a list (a[i]) an operation whose cost is independent of
the size of the list or the value of the index.

When items are appended or inserted, the array of references is resized.
Some cleverness is applied to improve the performance of appending items
repeatedly; when the array must be grown, some extra space is allocated so
the next few times don't require an actual resize.

----------------------------------------------------------------------------

6.17. How are dictionaries implemented?

Python's dictionaries are implemented as resizable hash tables.

Compared to B-trees, this gives better performance for lookup (the most
common operation by far) under most circumstances, and the implementation is
simpler.

----------------------------------------------------------------------------

6.18. Why must dictionary keys be immutable?

The hash table implementation of dictionaries uses a hash value calculated
from the key value to find the key. If the key were a mutable object, its
value could change, and thus its hash could change. But since whoever
changes the key object can't tell that is incorporated in a dictionary, it
can't move the entry around in the dictionary. Then, when you try to look up
the same object in the dictionary, it won't be found, since its hash value
is different; and if you try to look up the old value, it won't be found
either, since the value of the object found in that hash bin differs.

If you think you need to have a dictionary indexed with a list, try to use a
tuple instead. The function tuple(l) creates a tuple with the same entries
as the list l.

Some unacceptable solutions that have been proposed:

- Hash lists by their address (object ID). This doesn't work because if you
construct a new list with the same value it won't be found; e.g.,

      d = {[1,2]: '12'}
      print d[[1,2]]

will raise a KeyError exception because the id of the [1,2] used in the
second line differs from that in the first line. In other words, dictionary
keys should be compared using '==', not using 'is'.

- Make a copy when using a list as a key. This doesn't work because the list
(being a mutable object) could contain a reference to itself, and then the
copying code would run into an infinite loop.

- Allow lists as keys but tell the user not to modify them. This would allow
a class of hard-to-track bugs in programs that I'd rather not see; it
invalidates an important invariant of dictionaries (every value in d.keys()
is usable as a key of the dictionary).

- Mark lists as read-only once they are used as a dictionary key. The
problem is that it's not just the top-level object that could change its
value; you could use a tuple containing a list as a key. Entering anything
as a key into a dictionary would require marking all objects reachable from
there as read-only -- and again, self-referential objects could cause an
infinite loop again (and again and again).

There is a trick to get around this if you need to, but use it at your own
risk: You can wrap a mutable structure inside a class instance which has
both a __cmp__ and a __hash__ method.

       class listwrapper:
            def __init__(self, the_list):
                  self.the_list = the_list
            def __cmp__(self, other):
                  return self.the_list == other.the_list
            def __hash__(self):
                  l = self.the_list
                  result = 98767 - len(l)*555
                  for i in range(len(l)):
                       try:
                            result = result + (hash(l[i]) % 9999999) * 1001 + i
                       except:
                            result = (result % 7777777) + i * 333
                  return result

Note that the hash computation is complicated by the possibility that some
members of the list may be unhashable and also by the possibility of
arithmetic overflow.

You must make sure that the hash value for all such wrapper objects that
reside in a dictionary (or other hash based structure), remain fixed while
the object is in the dictionary (or other structure).

Furthermore it must always be the case that if o1 == o2 (ie
o1.__cmp__(o2)==0) then hash(o1)==hash(o2) (ie, o1.__hash__() ==
o2.__hash__()), regardless of whether the object is in a dictionary or not.
If you fail to meet these restrictions dictionaries and other hash based
structures may misbehave!

In the case of listwrapper above whenever the wrapper object is in a
dictionary the wrapped list must not change to avoid anomalies. Don't do
this unless you are prepared to think hard about the requirements and the
consequences of not meeting them correctly. You've been warned!

----------------------------------------------------------------------------

6.19. How the heck do you make an array in Python?

["this", 1, "is", "an", "array"]

Lists are arrays in the C or Pascal sense of the word (see question 6.16).
The array module also provides methods for creating arrays of fixed types
with compact representations (but they are slower to index than lists). Also
note that the Numerics extensions and others define array-like structures
with various characteristics as well.

To get Lisp-like lists, emulate cons cells

        lisp_list = ("like",  ("this",  ("example", None) ) )

using tuples (or lists, if you want mutability). Here the analogue of lisp
car is lisp_list[0] and the analogue of cdr is lisp_list[1]. Only do this if
you're sure you really need to (it's usually a lot slower than using Python
lists).

Think of Python lists as mutable heterogeneous arrays of Python objects (say
that 10 times fast :) ).

----------------------------------------------------------------------------

6.20. Why doesn't list.sort() return the sorted list?

In situations where performance matters, making a copy of the list just to
sort it would be wasteful. Therefore, list.sort() sorts the list in place.
In order to remind you of that fact, it does not return the sorted list.
This way, you won't be fooled into accidentally overwriting a list when you
need a sorted copy but also need to keep the unsorted version around.

As a result, here's the idiom to iterate over the keys of a dictionary in
sorted orted:

            keys = dict.keys()
            keys.sort()
            for key in keys:
                    ...do whatever with dict[key]...

----------------------------------------------------------------------------

6.21. How do you specify and enforce an interface spec in Python?

An interfaces specification for a module as provided by languages such as
C++ and java describes the prototypes for the methods and functions of the
module. Many feel that compile time enforcement of interface specifications
help aid in the construction of large programs. Python does not support
interface specifications directly, but many of their advantages can be
obtained by an appropriate test discipline for components, which can often
be very easily accomplished in Python.

A good test suite for a module can at once provide a regression test and
serve as a module interface specification (even better since it also gives
example usage). Look to many of the standard libraries which often have a
"script interpretation" which provides a simple "self test." Even modules
which use complex external interfaces can often be tested in isolation using
trivial "stub" emulations of the external interface.

An appropriate testing discipline (if enforced) can help build large complex
applications in Python as well as having interface specifications would do
(or better). Of course Python allows you to get sloppy and not do it. Also
you might want to design your code with an eye to make it easily tested.

----------------------------------------------------------------------------

6.22. Why do all classes have the same type? Why do instances all have the
same type?

The Pythonic use of the word "type" is quite different from common usage in
much of the rest of the programming language world. A "type" in Python is a
description for an object's operations as implemented in C. All classes have
the same operations implemented in C which sometimes "call back" to
differing program fragments implemented in Python, and hence all classes
have the same type. Similarly at the C level all class instances have the
same C implementation, and hence all instances have the same type.

Remember that in Python usage "type" refers to a C implementation of an
object. To distinguish among instances of different classes use
Instance.__class__, and also look to 4.47. Sorry for the terminological
confusion, but at this point in Python's development nothing can be done!

----------------------------------------------------------------------------

6.23. Why isn't all memory freed when Python exits?

Objects referenced from Python module global name spaces are not always
deallocated when Python exits.

This may happen if there are circular references (see question 4.17). There
are also certain bits of memory that are allocated by the C library that are
impossible to free (e.g. a tool like Purify will complain about these).

But in general, Python 1.5 and beyond (in contrast with earlier versions) is
quite agressive about cleaning up memory on exit.

If you want to force Python to delete certain things on deallocation use the
sys.exitfunc hook to force those deletions. For example if you are debugging
an extension module using a memory analysis tool and you wish to make Python
deallocate almost everything you might use an exitfunc like this one:

      import sys

      def my_exitfunc():
           print "cleaning up"
           import sys
           # do order dependant deletions here
           ...
           # now delete everything else in arbitrary order
           for x in sys.modules.values():
                d = x.__dict__
                for name in d.keys():
                     del d[name]

      sys.exitfunc = my_exitfunc

Other exitfuncs can be less drastic, of course.

(In fact, this one just does what Python now already does itself; but the
example of using sys.exitfunc to force cleanups is still useful.)

----------------------------------------------------------------------------

6.24. Why no class methods or mutable class variables?

The notation

        instance.attribute(arg1, arg2)

usually translates to the equivalent of

        Class.attribute(instance, arg1, arg2)

where Class is a (super)class of instance. Similarly

        instance.attribute = value

sets an attribute of an instance (overriding any attribute of a class that
instance inherits).

Sometimes programmers want to have different behaviours -- they want a
method which does not bind to the instance and a class attribute which
changes in place. Python does not preclude these behaviours, but you have to
adopt a convention to implement them. One way to accomplish this is to use
"list wrappers" and global functions.

       def C_hello():
             print "hello"

       class C:
            hello = [C_hello]
            counter = [0]

        I = C()

Here I.hello[0]() acts very much like a "class method" and I.counter[0] = 2
alters C.counter (and doesn't override it). If you don't understand why
you'd ever want to do this, that's because you are pure of mind, and you
probably never will want to do it! This is dangerous trickery, not
recommended when avoidable. (Inspired by Tim Peter's discussion.)

----------------------------------------------------------------------------

6.25. Why are default values sometimes shared between objects?

It is often expected that a function CALL creates new objects for default
values. This is not what happens. Default values are created when the
function is DEFINED, that is, there is only one such object that all
functions refer to. If that object is changed, subsequent calls to the
function will refer to this changed object. By definition, immutable objects
(like numbers, strings, tuples, None) are safe from change. Changes to
mutable objects (like dictionaries, lists, class instances) is what causes
the confusion.

Because of this feature it is good programming practice not to use mutable
objects as default values, but to introduce them in the function. Don't
write:

            def foo(dict={}):  # XXX shared reference to one dict for all calls
                ...

but:

            def foo(dict=None):
                    if dict is None:
                            dict = {} # create a new dict for local namespace

See page 182 of "Internet Programming with Python" for one discussion of
this feature. Or see the top of page 144 or bottom of page 277 in
"Programming Python" for another discussion.

----------------------------------------------------------------------------

6.26. Why no goto?

Actually, you can use exceptions to provide a "structured goto" that even
works across function calls. Many feel that exceptions can conveniently
emulate all reasonable uses of the "go" or "goto" constructs of C, Fortran,
and other languages. For example:

       class label: pass # declare a label
       try:
            ...
            if (condition): raise label() # goto label
            ...
       except label: # where to goto
            pass
       ...

This doesn't allow you to jump into the middle of a loop, but that's usually
considered an abuse of goto anyway. Use sparingly.

----------------------------------------------------------------------------

6.27. How do you make a higher order function in Python?

You have two choices: you can use default arguments and override them or you
can use "callable objects." For example suppose you wanted to define
linear(a,b) which returns a function f where f(x) computes the value a*x+b.
Using default arguments:

         def linear(a,b):
             def result(x, a=a, b=b):
                 return a*x + b
             return result

Or using callable objects:

         class linear:
            def __init__(self, a, b):
                self.a, self.b = a,b
            def __call__(self, x):
                return self.a * x + self.b

In both cases:

         taxes = linear(0.3,2)

gives a callable object where taxes(10e6) == 0.3 * 10e6 + 2.

The defaults strategy has the disadvantage that the default arguments could
be accidentally or maliciously overridden. The callable objects approach has
the disadvantage that it is a bit slower and a bit longer. Note however that
a collection of callables can share their signature via inheritance. EG

          class exponential(linear):
             # __init__ inherited
             def __call__(self, x):
                 return self.a * (x ** self.b)

On comp.lang.python, zenin@bawdycaste.org points out that an object can
encapsulate state for several methods in order to emulate the "closure"
concept from functional programming languages, for example:

        class counter:
            value = 0
            def set(self, x): self.value = x
            def up(self): self.value=self.value+1
            def down(self): self.value=self.value-1

        count = counter()
        inc, dec, reset = count.up, count.down, count.set

Here inc, dec and reset act like "functions which share the same closure
containing the variable count.value" (if you like that way of thinking).

----------------------------------------------------------------------------

6.28. Why do I get a SyntaxError for a 'continue' inside a 'try'?

This is an implementation limitation, caused by the extremely simple-minded
way Python generates bytecode. The try block pushes something on the "block
stack" which the continue would have to pop off again. The current code
generator doesn't have the data structures around so that 'continue' can
generate the right code.

Note that JPython doesn't have this restriction!

----------------------------------------------------------------------------

6.29. Why can't raw strings (r-strings) end with a backslash?

More precisely, they can't end with an odd number of backslashes: the
unpaired backslash at the end escapes the closing quote character, leaving
an unterminated string.

Raw strings were designed to ease creating input for processors (chiefly
regular expression engines) that want to do their own backslash escape
processing. Such processors consider an unmatched trailing backslash to be
an error anyway, so raw strings disallow that. In return, they allow you to
pass on the string quote character by escaping it with a backslash. These
rules work well when r-strings are used for their intended purpose.

If you're trying to build Windows pathnames, note that all Windows system
calls accept forward slashes too:

        f = open("/mydir/file.txt") # works fine!

If you're trying to build a pathname for a DOS command, try e.g. one of

        dir = r"\this\is\my\dos\dir" "\\"
        dir = r"\this\is\my\dos\dir\ "[:-1]
        dir = "\\this\\is\\my\\dos\\dir\\"

----------------------------------------------------------------------------

6.30. Why can't I use an assignment in an expression?

Many people used to C or Perl complain that they want to be able to use e.g.
this C idiom:

        while (line = readline(f)) {
            ...do something with line...
        }

where in Python you're forced to write this:

        while 1:
            line = f.readline()
            if not line:
                break
            ...do something with line...

This issue comes up in the Python newsgroup with alarming frequency --
search Deja News for past messages about assignment expression. The reason
for not allowing assignment in Python expressions is a common, hard-to-find
bug in those other languages, caused by this construct:

        if (x = 0) {
            ...error handling...
        }
        else {
            ...code that only works for nonzero x...
        }

Many alternatives have been proposed. Most are hacks that save some typing
but use arbitrary or cryptic syntax or keywords, and fail the simple
criterion that I use for language change proposals: it should intuitively
suggest the proper meaning to a human reader who has not yet been introduced
with the construct.

The earliest time something can be done about this will be with Python 2.0
-- if it is decided that it is worth fixing. An interesting phenomenon is
that most experienced Python programmers recognize the "while 1" idiom and
don't seem to be missing the assignment in expression construct much; it's
only the newcomers who express a strong desire to add this to the language.

One fairly elegant solution would be to introduce a new operator for
assignment in expressions spelled ":=" -- this avoids the "=" instead of
"==" problem. It would have the same precedence as comparison operators but
the parser would flag combination with other comparisons (without
disambiguating parentheses) as an error.

Finally -- there's an alternative way of spelling this that seems attractive
but is generally less robust than the "while 1" solution:

        line = f.readline()
        while line:
            ...do something with line...
            line = f.readline()

The problem with this is that if you change your mind about exactly how you
get the next line (e.g. you want to change it into sys.stdin.readline()) you
have to remember to change two places in your program -- the second one
hidden at the bottom of the loop.

----------------------------------------------------------------------------

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From Amos@digicool.com  Thu Jul  8 01:56:46 1999
From: Amos@digicool.com (Amos Latteier)
Date: Thu, 08 Jul 99 00:56:46 GMT
Subject: Zope Weekly News - Wed, 7 Jul 1999
Message-ID: <mt2.0-7243-931395406@news.informatik.uni-bonn.de>

Hello,

It's been a fairly uneventful week in Zopeland. As always lots of people
are asking questions and providing good answers. But this week's seen
few announcements and software releases, perhaps because of the holiday.
Another Zope alpha should be out soon, and that's sure to generate some
activity.

  * Anthony Pfrunder posted an update about his binary distribution of
Zope 2.0 alpha for Windows and an upcoming project to make Zope work
better with the Python Imaging Library and OpenGL.
  
  http://student.uq.edu.au/~s341625
  http://www.zope.org/pipermail/zope/1999-July/006298.html 
  
  * The unstoppable Martijn Pieters posted a patch to allow customizing
tree tag decoration. Now longer will you have to use those tired plus
and minus boxes.
  
  http://www.zope.org/pipermail/zope/1999-July/006401.html
  
  * Paul Everitt announced a press release detailing how Digital
Creations and UserLand are making Zope and Frontier play nicely
together.
  
  http://biz.yahoo.com/prnews/990707/tx_digital_1.html
  
  * Over on zope-dev list David Jacobs started an interesting discussion
of enhancing Zope security features.
  
  http://www.zope.org/pipermail/zope-dev/1999-July/000771.html
  http://www.zope.org/pipermail/zope-dev/1999-July/000773.html
  
  * Digital Creations intern Cathi Davey posted documentation to the
zope-dev list about some additional type converting facilities she's
added to ZPublisher.
  
  http://www.zope.org/pipermail/zope-dev/1999-July/000724.html
  
Until next week.

-Amos

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

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From fleck@informatik.uni-bonn.de  Sat Jul 10 08:49:28 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Sat, 10 Jul 99 07:49:28 GMT
Subject: [fm] REalizer 0.1
Message-ID: <mt2.0-16623-931592968@news.informatik.uni-bonn.de>

  REalizer 0.1
  Slayne - July 05th 1999, 18:15 EST

  REalizer is a GUI for entering and testing regular expressions provided
  by the python re module.

  Changes: First release.

      Download:http://www.globalserve.net/~catlee/REalizer.py

                  Author: Chris AtLee
                 License: GPL
                Category: Development/Tools
              Depends on: Python

  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.globalserve.net/~catlee/REalizer.py">REalizer 0.1</A>
- GUI for entering and testing regular expressions provided by the python re
module.  (05-Jul-99)

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From fleck@informatik.uni-bonn.de  Sat Jul 10 08:52:08 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Sat, 10 Jul 99 07:52:08 GMT
Subject: [fm] gimp-python 0.4
Message-ID: <mt2.0-16623-931593128@news.informatik.uni-bonn.de>

  gimp-python 0.4
  james - July 05th 1999, 12:13 EST

  Gimp-Python is a set of python modules that allow you to write plugins
  for the GIMP in python. You get the best of both worlds, with all the
  power of the C plugin interface available, and the automatic GUI
  generation of Script-Fu. This plugin is also good if you don't like
  programming in scheme, perl or tcl.

  Changes: Added gimp-1.1 support (it should still work with gimp-1.0),
  made some incompatible changes to the API (removed the drawable type,
  and moved all its functionality to the layer and channel types), added
  a script-fu like interface module that handles all the GUI stuff of a
  plugin for you -- see the example plugins for details.

      Download:ftp://ftp.daa.com.au/pub/james/pygimp/
      Homepage:http://www.daa.com.au/~james/pygimp/

                  Author: James Henstridge
                 License: GPL
                Category: Development/Python Modules
              Depends on: gimp, python, pygtk

  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.daa.com.au/~james/pygimp/">gimp-python 0.4</A> -
set of python modules that allow you to write plug-ins for the
<A HREF="http://www.gimp.org">GIMP</A> (GNU Image Manipulation Program)
in Python.  (05-Jul-99)

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From neelk@alum.mit.edu  Sat Jul 10 08:53:46 1999
From: neelk@alum.mit.edu (neelk@alum.mit.edu)
Date: Sat, 10 Jul 99 07:53:46 GMT
Subject: Signature 0.1
Message-ID: <mt2.0-16623-931593226@news.informatik.uni-bonn.de>

Signature.py is a module that makes reflecting on the function call
signatures of callable objects a lot easier. A common question in
Python is "How do I ask the interpreter what arguments a function
takes?" and while the information is obviously available, I haven't
found any simple, high-level interfaces to it.

That's why I wrote Signature -- it's useful enough that it's made it
into my personal library of frequently-used utilities.

You can find it at:

  http://www.sff.net/people/neelk/free-software/Signature.py

Caveats/TODO:

o I don't know if it will work on JPython -- I exploited a lot of
  undocumented object attributes to figure out what the call signature
  is, and I have no idea if the same data is available there.

o I haven't figured out how to look into C builtins yet -- anyone
  who can teach me how to do this from within Python will earn my
  undying gratitude. :)

Example of use:

    >>> def foo(x, y, z=-1.0, *args, **kw):
    ...     return (x+y)**z
    ...
    >>> f = Signature(foo)

    >>> print 'ordinary arglist:', f.ordinary_args()
    ordinary arglist: ('x', 'y', 'z')

    >>> print 'special_args:', f.special_args()
    special_args: {'keyword': 'kw', 'positional': 'args'}

    >>> print 'full arglist:', f.full_arglist()
    full arglist: ['x', 'y', 'z', 'args', 'kw']

    >>> print 'defaults:', f.defaults()
    defaults: {'z': -1.0}

    >>> print 'signature:', str(f)
    signature: foo(x, y, z=-1.0, *args, **kw)


Neel

<P><A HREF="http://www.sff.net/people/neelk/free-software/Signature.py">
Signature 0.1</A> - for reflecting on the function call signatures of
callable objects.  (09-Jul-99)

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From neelk@alum.mit.edu  Sat Jul 10 08:53:46 1999
From: neelk@alum.mit.edu (neelk@alum.mit.edu)
Date: Sat, 10 Jul 99 07:53:46 GMT
Subject: Signature 0.1
Message-ID: <7m9tnh$6qg$59@rks1.urz.tu-dresden.de>

Signature.py is a module that makes reflecting on the function call
signatures of callable objects a lot easier. A common question in
Python is "How do I ask the interpreter what arguments a function
takes?" and while the information is obviously available, I haven't
found any simple, high-level interfaces to it.

That's why I wrote Signature -- it's useful enough that it's made it
into my personal library of frequently-used utilities.

You can find it at:

  http://www.sff.net/people/neelk/free-software/Signature.py

Caveats/TODO:

o I don't know if it will work on JPython -- I exploited a lot of
  undocumented object attributes to figure out what the call signature
  is, and I have no idea if the same data is available there.

o I haven't figured out how to look into C builtins yet -- anyone
  who can teach me how to do this from within Python will earn my
  undying gratitude. :)

Example of use:

    >>> def foo(x, y, z=-1.0, *args, **kw):
    ...     return (x+y)**z
    ...
    >>> f = Signature(foo)

    >>> print 'ordinary arglist:', f.ordinary_args()
    ordinary arglist: ('x', 'y', 'z')

    >>> print 'special_args:', f.special_args()
    special_args: {'keyword': 'kw', 'positional': 'args'}

    >>> print 'full arglist:', f.full_arglist()
    full arglist: ['x', 'y', 'z', 'args', 'kw']

    >>> print 'defaults:', f.defaults()
    defaults: {'z': -1.0}

    >>> print 'signature:', str(f)
    signature: foo(x, y, z=-1.0, *args, **kw)


Neel

<P><A HREF="http://www.sff.net/people/neelk/free-software/Signature.py">
Signature 0.1</A> - for reflecting on the function call signatures of
callable objects.  (09-Jul-99)

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From andrew@andrewcooke.free-online.co.uk  Sun Jul 11 12:58:40 1999
From: andrew@andrewcooke.free-online.co.uk (Andrew Cooke)
Date: Sun, 11 Jul 99 11:58:40 GMT
Subject: Alfajor - Cookie Filter
Message-ID: <mt2.0-5604-931694320@news.informatik.uni-bonn.de>

Hi,

Alfajor is an http cookie filter, written in Python with an optional
GUI. It acts as an http proxy (you must configure your browser to use
it) and can either contact sites directly or work with a second proxy
(eg. a cache).

The program allows cookies to be sent from your browser to any address
which matches a list of regular expressions. The GUI allows the filter
to be turned on and off, sites to be added or removed as they are
accessed, and the list of regular expressions to be edited.

The program is (c) Andrew Cooke 1999 and released under the GPL.

For more info, please look at
http://www.andrewcooke.free-online.co.uk/jara/alfajor/index.html

Thanks,
Andrew


Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

<P><A HREF="http://www.andrewcooke.free-online.co.uk/jara/alfajor/index.html">Alfajor</A> -
configurable HTTP cookie filter written in Python.  (10-Jul-99)

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From akuchlin@mems-exchange.org  Mon Jul 12 02:45:23 1999
From: akuchlin@mems-exchange.org (Andrew M. Kuchling)
Date: Mon, 12 Jul 99 01:45:23 GMT
Subject: Python SECS-I implementation
Message-ID: <mt2.0-20685-931743923@news.informatik.uni-bonn.de>

The MEMS Exchange (http://www.mems-exchange.org) is making secs_i.py,
a Python implementation of the SECS-I protocol, freely available.
For more information, see the following URL:

    http://www.mems-exchange.org/exchange/software/secs-i/

SECS-I is the SEMI Equipment Control Standard I, a protocol supported
by a lot of the equipment used in semiconductor fabs.  We needed it to
control the optics of the Leica INM200 microscope, but it may be
useful to other people who want to talk to various pieces of
semiconductor manufacturing equipment.  (I was unable to find a free
implementation of SECS-I, though various companies sell commercial
libraries.) 

The code has actually been available for a while, buried inside the
Remote Microscope distribution that's also available from the MEMS
Exchange; secs_i.py is being made separately available to make it
easier for outsiders to find the code.  Bug reports and improvements
are welcome.

== 
A.M. Kuchling			http://starship.python.net/crew/amk/
God made the Idiot for practice, and then He made the School Board.
    -- Mark Twain

<P><A HREF="http://www.mems-exchange.org/exchange/software/secs-i/">SECS-I
implementation</A> - Python implementation of the SEMI Equipment Control
Standard protocol for equipment used in semiconductor fabs.  (11-Jul-99)

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From fleck@informatik.uni-bonn.de  Tue Jul 13 16:37:35 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Tue, 13 Jul 99 15:37:35 GMT
Subject: [fm] HtmlXtract redhog.0
Message-ID: <mt2.0-29824-931880255@news.informatik.uni-bonn.de>

   HtmlXtract redhog.0
   Egil Moeller - July 06th 1999, 23:12 EST

   HtmlXtract is a text-utility that let you extract, remove or replace a block
   from a HTML-document. The block to operate on is pointed out by a "path"
   through the nested blocks (For example, the path html.body.table{2}.tr.td{3}
   points out the third td inside the first tr inside the second table (inside the
   body inside html)).
   HtmlXtract is divided in three parts; a generic part (That can be used to
   xtract, remove or replace parts from any block-oriented language), a
   Html-specific part, and a command-line front-end. The first two parts may be
   included in any Python-program as ordinary modules.

   Changes: This is the first release.

   Download:
   http://a190.ryd.student.liu.se/Projects/Programming/Xtract/Xtract.tar.gz

                     Author:Egil Möller
                    License:GPL
                   Category:Console/Text Utilities

   Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://a190.ryd.student.liu.se/Projects/Programming/Xtract/">HtmlXtract
redhog.0</A> - module for extracting, removing or replacing parts of a
document in any block-oriented language (Non-regular, context-free),
such as HTML or LaTeX.  (06-Jul-99)

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From joe@strout.net  Tue Jul 13 16:38:40 1999
From: joe@strout.net (Joe Strout)
Date: Tue, 13 Jul 99 15:38:40 GMT
Subject: PIDDLE 1.0a3
Message-ID: <mt2.0-29824-931880320@news.informatik.uni-bonn.de>

I'm pleased to announce the third alpha release of PIDDLE (Plug-In
Drawing, Does Little Else).  PIDDLE is a cross-platform, cross-media
drawing API; by choosing the desired backend renderer, your Python
program can generate output to the PDF, EPS, TK, MacOS QuickDraw, a PIL
canvas (and from there to PNG, GIF, JPEG, etc.), and others.

This version adds a unified testing framework, and a number of bug
fixes.  To download, visit the PIDDLE home page:

      http://www.strout.net/python/piddle/


PIDDLE is written in 100% Python, but some backends require extensions
(such as PIL) or may work on only certain platforms (such as MacOS
QuickDraw).

Comments and feedback are welcome; visit the mailing list at
http://www.egroups.com/list/pythonpiddle/info.html to join the
discussion.

Cheers,
-- Joe

== 
,------------------------------------------------------------------.
|    Joseph J. Strout           Biocomputing -- The Salk Institute |
|    joe@strout.net             http://www.strout.net              |
`------------------------------------------------------------------'

<P><A HREF="http://www.strout.net/python/piddle/">PIDDLE v1.0a3</A> -
drawing API with backends that do the actual drawing to a variety of
formats, including PDF, Postscript, MacOS QuickDraw, Tk, PIL, and
eventually OpenGL and Windows.  (12-Jul-99)

-- 
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From tismer@appliedbiometrics.com  Tue Jul 13 16:39:13 1999
From: tismer@appliedbiometrics.com (Christian Tismer)
Date: Tue, 13 Jul 99 15:39:13 GMT
Subject: Stackless Python 0.3
Message-ID: <mt2.0-29824-931880353@news.informatik.uni-bonn.de>

ANNOUNCING:

               Stackless Python 0.3
           A Python Implementation Which
             Does Not Use The C Stack

What is it?
A plugin-replacement for core Python.
It should run any program which runs under Python 1.5.2 .
But it does not need space on the C stack.

Why did I write it?
Stackless Python was never written before (afaik), since it
was said to be impossible without major rewrites of core Python.
I am proving the controverse:
It is easy to write, just hard to think.

Recent changes:
Version 0.3 has been written while developing a continuation
module which is about to ship. A couple of enhancements and
changes were necessary to make continuations fly. Some drastic
changes to frame management have been made. Stackless Python
is now also able to keep track of recursive interpreter
incarnations and to detect/resolve possible collisions
between their frames. As a proof of concept, continuationsmodule.c
will ship in a few days.

Who needs it?
At the moment, this is only useful for C programmers
who want to try certain new ideas. Hardcore stuff.
It allows to modify the current execution state by
changing the frame stack chain without restictions,
and it allows for pluggable interpreters on a per-frame-basis.

The possibilities are for instance:

Continuations, with which we will build Coroutines and Generators

Restartable exceptions and Persistent execution state
are the next topic to think about. They are possible.

Stackless extension modules can be built. The new builtin
stackless "map" function is a small example for this.

Coroutines are able to run at the speed of
a single C function call, which makes them a considerable
alternative in certain algorithms.
This is no longer a speculation since I have working
coroutine prototypes, written with continuations.

Status of the project:
Stackless-ness has been implemented and tested with pystone.
pystone works correctly and is about 10 % slower than
with standard Python.

What I need at the moment is
- time to do the right design of coroutines on top of continuations
- your input, your testing, critics and hints.

Some still rough documentation is available at
http://www.pns.cc/stackless/stackless.htm

Source code and a VC++6.0 build for Windows can be found
from the document or directly from
ftp://ftp.pns.cc/pub/stackless_990712.zip
ftp://ftp.pns.cc/pub/stackless_990712_win32.zip

cheers - chris

== 
Christian Tismer             :^)   <mailto:tismer@appliedbiometrics.com>
Applied Biometrics GmbH      :     Have a break! Take a ride on Python's
Kaiserin-Augusta-Allee 101   :    *Starship* http://starship.python.net
10553 Berlin                 :     PGP key -> http://wwwkeys.pgp.net
PGP Fingerprint       E182 71C7 1A9D 66E9 9D15  D3CC D4D7 93E2 1FAE F6DF
     we're tired of banana software - shipped green, ripens at home

<P><A HREF="http://www.pns.cc/stackless/stackless.htm">Stackless Python
0.3</A> - a version of Python 1.5.2 that does not need space on the C
stack.  (12-Jul-99)

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From grove@infotek.no  Thu Jul 15 12:02:09 1999
From: grove@infotek.no (Geir Ove Grønmo)
Date: Thu, 15 Jul 99 11:02:09 GMT
Subject: tmproc 0.20, a Topic Maps implementation
Message-ID: <mt2.0-4090-932036529@news.informatik.uni-bonn.de>

Hello,

I'm pleased to announce the second release of tmproc, a Topic Map
processor. This release is updated according to the final standard.

Suggestions and bug reports should be sent to: grove@infotek.no

Enjoy!

Geir O. Grønmo

--------------------------------------------------------------------------

Title: tmproc

Version: 0.20
Released: July 14th 1999

Author: Geir O. Grønmo, grove@infotek.no

Homepage: http://www.infotek.no/~grove/software/tmproc/index.html

- --
>>> What's new?

 o This version supports the final release of the standard.
 o Minor bugfixes
 o Works with the Java Platform (JPython[1])

- --
>>> What is tmproc?

tmproc is an implementation of the new international standard ISO/IEC
13250 Topic Maps[2]. tmproc is written in Python, and should work on
any platform to which Python have been ported - including the Java
Platform.

- --
>>> What are Topic Maps?

'Topic Maps' is a new international standard (ISO/IEC 13250) for
layering multidimensional topic spaces on top of information
assets. The standard covers concepts like topics, associations,
occurrences and facets/metadata. Topic Maps are expected to have a
major impact on future information systems.

- --
>>> Features

 o Import, export, query and manipulation of topic maps.

 o Full set of extensible topic map classes with clearly defined
   interfaces.

 o Optional architectural processing [requires xmlarch].

 o Introduction and reference documentation.

 o Statistical and information printing classes

 o Command line utility for interactive exploration

- --
>>> Requirements
   
  - Python 1.5.1 or newer [3]
  - An SGML/XML parser with a SAX driver
  - SAX for Python [4]
  - xmlarch 0.25, optional unless architectural processing is needed [5]

- --
>>> Licence

tmproc is free for both non-commercial and commercial
use. Redistribution of tmproc in commercial products requires another
licence. See [*] for detailed licence information.

- --
>>> References

[1] http://www.jpython.org/
[2] http://www.ornl.gov/sgml/SC34/
[3] http://www.python.org/
[4] http://www.stud.ifi.uio.no/~larsga/download/python/xml/saxlib.html
[5] http://www.infotek.no/~grove/software/xmlarch/index.html

[*] http://www.infotek.no/~grove/software/tmproc/licence.html

--------------------------------------------------------------------------

<P><A HREF="http://www.infotek.no/~grove/software/tmproc/index.html">tmproc
0.20</A> - an implementation of Topic Maps, a new international
standard (ISO/IEC 13250:1999) for layering multidimensional topic
spaces on top of information assets.  (13-Jul-99)

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From Amos@digicool.com  Thu Jul 15 12:02:50 1999
From: Amos@digicool.com (Amos Latteier)
Date: Thu, 15 Jul 99 11:02:50 GMT
Subject: Zope Weekly News - Wed, 14 Jul 1999
Message-ID: <mt2.0-4090-932036570@news.informatik.uni-bonn.de>

Hello, 

Another Zope alpha release is out. It looks like we're getting fairly
close to a Zope 2.0 beta release. Many intrepid people have been using
the alpha releases and submitting patches and bug reports. Soon Zope 2
should be ready for wider consumption.

 * Jim Fulton announced the availability of Zope 2.0a4. This version
fixes a lot of bugs and adds a few minor features. It looks like this
may be the last alpha release.

  http://www.zope.org/Download/Releases/Zope-2.0.0a4
  http://www.zope.org/Download/Releases/Zope-2.0.0a4/CHANGES.txt

 * Over on the zope-dev list Bruce Perens offered a patch to make Image
object more flexible in the way they represent themselves in HTML.
Martijn Pieters followed up with additional improvements. Hours later
the enhancements were in CVS. Open source rocks!

  http://www.zope.org/pipermail/zope-dev/1999-July/000826.html

  * Christopher Petrilli posted a survey asking folks about what they
think of the Gadfly DA. Response was mixed, though many people seem to
find it useful.

  http://www.zope.org/pipermail/zope/1999-July/006457.html

  * Brian Lloyd posted a query about how to best allow people to upgrade
from the existing database format (BoboPOS) to the new ZODB format. Most
people seem to think that providing a conversion script is the best
option.

  http://www.zope.org/pipermail/zope/1999-July/006472.html

  * Alexander Staubo suggest some interesting management interface
improvements. Clearly this is an area of Zope that can be improved and
community efforts could really make a big difference.

  http://www.zope.org/pipermail/zope/1999-July/006554.html

  * Linux Developer's Network is looking for articles about Zope.

  http://www.zope.org/pipermail/zope/1999-July/006598.html
  http://linuxdev.net/

  * Kam Cheung started a remarkable good natured discussion about the
differences between Zope and Frontier. As more folks come to Frontier to
Zope it will be interesting to see what Zopistas can learn from them.

  http://www.zope.org/pipermail/zope/1999-July/006682.html

  * Apparently Zope 1.10.3 RPMs are available on Redhat's libc6 contrib
area.

  http://www.zope.org/pipermail/zope/1999-July/006665.html

  * What started out as a documentation bug post by Bruce Perens turned
into a discussion of the merits of various documentation formats and
which ones are best for open source projects. Right now official Zope
documentation is written in FrameMaker.

  http://www.zope.org/pipermail/zope/1999-July/006613.html

 * Anthony Pfrunder continues to improve his Zope 2 for Windows
distribution. It's now tentatively called Universal Zope Build System,
and includes various cool build tools. 

  http://www.zope.org/pipermail/zope-dev/1999-July/000835.html
  http://student.uq.edu.au/~s341625/


-Amos

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

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From jsight@pair.com  Thu Jul 15 12:07:14 1999
From: jsight@pair.com (Jesse D. Sightler)
Date: Thu, 15 Jul 99 11:07:14 GMT
Subject: [website] The pyPit software library.
Message-ID: <mt2.0-4090-932036834@news.informatik.uni-bonn.de>

Announcing the pyPit!
URL:  http://www.biddin.com/pyPit/

The pyPit is a fledgling attempt to develop an interactive library of
Python software libraries and code snippets.  Right now, there are fewer
than a dozen projects listed, but we are open for submissions.  The
system is based on a gadfly database, which will ultimately allow
keyword and other (as yet unannounced features).

For the moment, I am requesting that everyone submit their free software
projects for listing at http://www.biddin.com/pyPit/submit.html so that
we can have something to work with in order to prototype the full-system
in a more "real world" scenario (say, a few hundred software entries, in
a variety of categories).

Suggestions, and ideas for improvement as well as volunteers to work on
the project are certainly welcome.  

Enjoy.:)

== 
---------------
Jesse D. Sightler

<P><A HREF="http://www.biddin.com/pyPit/">PyPit</A> - interactive
library of contributed Python software libraries.  (15-Jul-99)

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From ajs@cs.monash.edu.au  Thu Jul 15 12:09:18 1999
From: ajs@cs.monash.edu.au (Andrew Snare)
Date: Thu, 15 Jul 99 11:09:18 GMT
Subject: PQueue 0.1a - Extension priority-queue module
Message-ID: <mt2.0-4090-932036958@news.informatik.uni-bonn.de>

This is the first release of a module I've just written, released under
the LGPL. It is available for download at:
	http://www.pigpond.com/~earthpig/PQueue-0.1a.tar.bz2

>From the documentation included with the release:

PQueue Extension Module for Python - 0.1a
=========================================

This C extension implements a priority-queue object using a fibonacci
heap as the underlying data structure. This data structure supports
the following operations with the given amortized time-complexity:

        - insert:       O(1)
        - find-min:     O(1)
        - extract-min:  O(lg N)
        - decrease-key: O(1)
        - increase-key: O(lg N)                 (== delete, insert)
        - delete:       O(lg N)                 (== decrease-key, extract-min)

This asymptotic behaviour compares favourably to more traditional
structures such as binomial heaps, at the cost of slightly higher
constant overheads.

This is the first public release of this extension -- feedback is both
welcome and encouraged. Thanks must go to James Henstridge <james@daa.com.au>
for providing such a nice autoconf system for extension modules, and
to Aaron Waters <arw@pythonpro.com> for providing the PyModules FAQ
resource and his pq3.py module (a slightly modified version of which
is included in this distribution for benchmarking purposes).

 - Andrew Snare <ajs@cs.monash.edu.au>
== 
#!/usr/bin/env python
print(lambda s:s+"("+`s`+")")\
('#!/usr/bin/env python\012print(lambda s:s+"("+`s`+")")\\\012')
print(lambda x:x%`x`)('print(lambda x:x%%`x`)(%s)')

For the web thingy:
<P><A HREF="http://www.pigpond.com/~earthpig/PQueue-0.1a.tar.bz2">PQueue
0.1a</A> - fast priority-queue extension module implemented in C.  (15-Jul-99)

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From fleck@informatik.uni-bonn.de  Thu Jul 15 12:11:32 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Thu, 15 Jul 99 11:11:32 GMT
Subject: [fm] PyGCS 1.3.2
Message-ID: <mt2.0-4272-932037092@news.informatik.uni-bonn.de>

  PyGCS 1.3.2
  Jeff Blaine - July 10th 1999, 12:03 EST

  PyGCS is a very stripped down MUD-like chat-server written entirely in
  Python. It has a single "room" and no large database to keep in memory
  and on disk. PyGCS has no embedded programming language. PyGCS is
  ideally meant to be a small multi-user real-time chat system for people
  who have a need to talk to more than one person at a time online. It
  fits somewhere in between the setup IRC uses (no walking between rooms
  so to speak) and the MUCK/MUSH/MOO style of server.

  Changes: Fixed a 'command stacking MUD client' bug which would crash the
  server. Tested code with newly released Python 1.5.2. Indented code to
  adhere to Python Style Guide for users wanting to use the source as a
  starting point. Two other tiny code cleanups.

  Download: ftp://ftp.shore.net/members2/j/jblaine/Source/pygcs-1.3.2.tar.gz
  Homepage: http://www.shore.net/~jblaine/code-GCS.html
 Changelog: http://www.shore.net/~jblaine/PyGCS_ChangeLog.txt

                  Author: Jeff Blaine
                 License: BSD type
                Category: Daemons/MUD
              Depends on: Python 1.5 or higher

  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.shore.net/~jblaine/code-GCS.html">PyGCS 1.3.2</A> -
stripped down MUD-like chat-server written entirely in Python.  (10-Jul-99)

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From fleck@informatik.uni-bonn.de  Thu Jul 15 12:12:56 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Thu, 15 Jul 99 11:12:56 GMT
Subject: TkGS Project to define a new Graphics Subsystem for Tk
Message-ID: <mt2.0-4272-932037176@news.informatik.uni-bonn.de>

From: Frederic BONNET <frederic.bonnet@ciril.fr>
Subject: ANNOUNCE: Creation of the TkGS mailing list
Date: 14 Jul 1999 02:51:24 -0700

I am pleased to announce the creation of a mailing list dedicated to the
TkGS project. The TkGS projects main goal is to define a new graphics
subsystem for Tk with device-independence in mind. You can find the complete
TkGS specification at:

        http://www.multimania.com/fbonnet/Tcl/TkGS/specs.htm

To subscribe, send an e-mail to:

        tkgs-list-subscribe@egroups.com

The web page for this list is located at:

        http://www.egroups.com/list/tkgs-list/

Happy reading!
== 
Frédéric BONNET                        frederic.bonnet@ciril.fr
---------------------------------------------------------------
"Theory may inform, but Practice convinces"
                                                    George Bain
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From tim_one@email.msn.com  Tue Jul 20 14:55:29 1999
From: tim_one@email.msn.com (Tim Peters)
Date: Tue, 20 Jul 99 13:55:29 GMT
Subject: Cyclops 0.9.4
Message-ID: <mt2.0-27614-932478929@news.informatik.uni-bonn.de>

http://www.python.org/ftp/python/contrib/System/Cyclops.py

# Module Cyclops version 0.9.4.
# Released to the public domain 18-Jul-1999,
# by Tim Peters (tim_one@email.msn.com).

Cyclops.py implements a CycleTracker class that provides major help in
finding and analyzing runtime cycles in Python programs.

Strong points:

+ Much faster than previous similar modules.  Searching for cycles
  takes time linear in the number of objects reachable from the
  registered objects plus the number of arcs connecting them, and all
  computation needed to display cycles is delayed until it's really
  needed (if ever). Tens of thousands of objects and hundreds of
  thousands of arcs can be analyzed in less than a minute on my creaky
  old P5-166 system.

+ Many kinds of optional output reports, from a simple listing of
  objects found in cycles, to a partitioning of cyclic objects into
  maximal strongly-connected components.

+ Easy to add new types to the set of objects CycleTracker knows how
  to "chase":  pass appropriate functions to a CycleTracker instance's
  chase_type() method.  It's done this way instead of via subclassing
  for speed.

+ An optional cycle-filter callback can be registered to ignore expected
  cycles (typically those created by the Python implementation itself).

Weak points:

+ The problems this module helps to address are inherently difficult, and
  CycleTracker doesn't make them any easier to understand or to fix -- it
  only helps identify what and where they are.  It's a tool, not a
  solution.

+ All the optional abilities make for a steep learning curve.

+ Registering objects can distort the behavior of the program under
  investigation, by keeping objects alive that would otherwise have died.
  See the module docstring for discussion and workarounds.

<P><A HREF="http://www.python.org/ftp/python/contrib/System/Cyclops.py">Cyclops.py
0.9.4</A> - tool for tracking cyclic structures in Python programs.  (19-Jul-99)

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From da@ski.org  Tue Jul 20 14:56:55 1999
From: da@ski.org (David Ascher)
Date: Tue, 20 Jul 99 13:56:55 GMT
Subject: Call for Panelists
Message-ID: <mt2.0-27614-932479015@news.informatik.uni-bonn.de>

Call for Panelists

The program for the O'Reilly Python Conference includes the following
moderated, 50-minute panels:

o Python Success Stories
	o Date: Monday, 23 August 1999
	o Moderator: Uche Ogbuji of FourThought LLC

o Joys and Pains of Building an Open-Source Community
	o Date: Tuesday, 24 August 1999
	o Moderator: Paul Everitt of Digital Creations

These panels are intended to be informal, structured discussions of the
topics by members of the python community.

In addition to panel members already determined, the program committee
invites conference attendees and members of the Python community to
participate.  We seek individuals who have successfully applied Python to
interesting computer problems in business, academics, or government; and
individuals who have been involved in Python-based open-source projects.

Interested parties should send e-mail by August 1 to monterey@egroups.com
with the following information:

 o Name, affiliation, phone number and e-mail address of the panelist

 o A paragraph on the successful use of Python, or relevant open-source
   project.

 o A brief biography of the panelist

 o Whether or not the panelist has registered to attend the conference

The O'Reilly Python conference is part of the O'Reilly Open Source
Convention (http://conferences.oreilly.com/) from August 21-24, 1999 in
Monterey, California.  This conference includes six concurrent conferences
featuring a wide array of exciting open-source technologies and
personalities.  The Python conference includes four tutorials, 15
presentations, birds-of-a-feather sessions, and more.

The Program Committe
Python Conference

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From Jeff Rush" <jrush@summit-research.com  Tue Jul 27 16:10:31 1999
From: Jeff Rush" <jrush@summit-research.com (Jeff Rush)
Date: Tue, 27 Jul 99 15:10:31 GMT
Subject: RPMs for mxDateTime, mxODBC-Solid, python-xml and Fnorb 1.01, Zope (rerelease)
Message-ID: <mt2.0-21715-933088231@news.informatik.uni-bonn.de>

RPMs for mxDateTime, mxODBC-Solid, python-xml and Fnorb 1.01, Zope
(rerelease)

I've packaged the Python extension modules, mxDateTime,
mxODBC (for Solid SQL only) and the Python-XML SIG's
'python-xml 0.5.1' as Red Hat RPMs.

The RPMs for the CORBA ORB Fnorb have been updated from
1.0 to 1.01, and the Zope RPMs have been re-released
(1.10.3-3) to fix packaging bugs, such as the omission of
Query/Splitter.so libraries needed by Confera, a Zope add-on.

All RPMs have been uploaded to the Red Hat Contrib network.

    http://starship.python.net/crew/jrush/

<P><A HREF="http://starship.python.net/crew/jrush/">RedHat RPMs</A> -
for mxDateTime, mxODBC-Solid, python-xml and Fnorb 1.01, Zope.  (21-Jul-99)

Jeff Rush <jrush@summit-research.com>

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From Amos@digicool.com  Tue Jul 27 16:11:02 1999
From: Amos@digicool.com (Amos Latteier)
Date: Tue, 27 Jul 99 15:11:02 GMT
Subject: Zope Weekly News - Wed, 21 Jul 1999
Message-ID: <mt2.0-21715-933088262@news.informatik.uni-bonn.de>

Zope 2.0 beta one should be out *very* soon. This week saw a lot of
screw tightening in preparation for the beta release. The public CVS
archive is temporarily frozen due to some re-organization but will open
up again when the beta release comes out.

Most of the traffic on the Zope lists was devoted to Zope community
members helping each other solve their various real world problems.

One of the most notable discussions this week started with a comparison
between Zope and other web development platforms with respect to xml
facilities. Folks at DC weighed in with their 2 cents on the subject
which includes the imminent release of a Zope product which will allow
access to xml objects in Zopish ways. Interestingly many community
members have similar ideas of what Zope needs in terms of xml support.
It will be exciting to see how Digital Creations and community members
collaborate on XML development efforts.
  
  * Chris Petrilli announced an new Zope mailing list, zope-announce. If
you're overwhelmed with the volume of the currently Zope lists, this one
could be for you.

  http://www.zope.org/mailman/listinfo/zope-announce/
  http://www.zope.org/pipermail/zope/1999-July/006993.html

  * Amos Latteier posted a roadmap details some plans for XML
development in Zope. Digital Creations will release an alpha XML Zope
product in the next couple days. 

  http://www.zope.org/pipermail/zope/1999-July/007010.html

  *  One of the best IT magazines on the German market, iX Magazine, has
a Zope article available in the August 1999 issue by Frank Tegtmeyer.

  http://www.heise.de/ix/
  http://www.heise.de/ix/artikel/1999/08/064/

  * Andreas Kostyrka announced Navigate 0-0-4. This product allows you
to control which objects are displayed.
 
  http://www.zope.org/pipermail/zope/1999-July/006969.html
  http://www.zope.org/Download/Contrib/

  * Arpad Kiss announced a simple Zope chart drawing tool.

  http://www.zope.org/pipermail/zope/1999-July/006964.html
  http://starship.python.net/crew/arpadk/downloads/Chart0.3.0.tar.gz

  * Andy Dustman announced a new Python interface for MySQL,
MySQLdb-0.0.3. This package includes a patch to use it with Zope's MySQL
database adapter. 

  http://www.zope.org/pipermail/zope/1999-July/006946.html
  http://starship.python.net/crew/adustman

  * Hurrah Internet now offers Zope hosting.

  http://www.hurrah.com/
  http://www.zope.org/Community/ZHP

  * Chris Petrilli posted a note about BLOBs and Zope database adapters
on the zope-dev list.

  http://www.zope.org/pipermail/zope-dev/1999-July/000863.html


See you next week.

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

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From nevink@earthlink.net  Tue Jul 27 16:15:45 1999
From: nevink@earthlink.net (nevin)
Date: Tue, 27 Jul 99 15:15:45 GMT
Subject: COMMERCIAL: C-Forge v1.3 (multi-user IDE)
Message-ID: <mt2.0-21715-933088545@news.informatik.uni-bonn.de>

Code Forge Inc is proud to announce C-Forge v1.3.

C-Forge is a multi-user integrated development environment that provides
full project management and complete edit/compile/debug cycle support.

Features include:

* Complete abstraction of the "makefile" concept,
* Project Manager for Visual presentation of project structure and
  component status using a dependency tree
* separate "desktop" area showing work in progress,  support for C/C++,
  Perl, Oracle ProC/C++, Tcl, Java, Python, Qt, Pascal, Free Pascal,
  FORTRAN, Modula-2 and Assembler, fully configurable integrated editor
  and more.

 New This Version:

  *  New integrated (detachable) multi-process log window
  *  Project-specific environment variables
  *  JavaScript support
  *  Etags/Ctags support
  *  Improved Tex/LaTex support

It is also our 2nd anniversary. We're throwing a 20%-50% off sale on
all our products! Please visit us at www.codeforge.com and download a
full featured evaluation version of C-Forge. (Free version also
available) Feedback is, as always,  welcome.

For more please come to our web site, located at
http://www.codeforge.com

== 
Nevin Kaplan - Director of Marketing
Code Forge, Inc.
www.codeforge.com

<P><A HREF="http://www.codeforge.com">C-Forge v1.3.</A> - commercial
IDE with Python support.  (22-Jul-99)

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From Amos@digicool.com  Tue Jul 27 16:18:52 1999
From: Amos@digicool.com (Amos Latteier)
Date: Tue, 27 Jul 99 15:18:52 GMT
Subject: XMLDocument 1.0a1
Message-ID: <mt2.0-21715-933088731@news.informatik.uni-bonn.de>

I am pleased to announce the first alpha release of XML Document. XML
Document allows you to use xml objects in the Zope environment. You can
create xml documents in Zope and leverage Zope to format, query, and
manipulate xml.

  http://www.zope.org/Download/XMLDocument

This release requires Zope 2.0x and the pyexpat parser which will be
distributed with Zope come Zope 2.0b1. Until the Zope beta release you
can get pyexpat from the Python xml-sig's xml package.

  http://www.python.org/sigs/xml-sig

I'd love feedback on the functionality and design of this product. I
think that it has a lot of potential. Also I encourage contributions on
this project since I do not have a lot of time to spend on it myself.

Happy xml hacking!

-Amos

P.S. Install it like a normal Zope product, i.e. ungzip and untar in
inside your Zope directory. If you are using the xml-sig pyexpat, Zope
will expect to find it in xml.parsers.pyexpat.

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

_______________________________________________
XML-SIG maillist  -  XML-SIG@python.org
http://www.python.org/mailman/listinfo/xml-sig

<P><A HREF="http://www.zope.org/Download/XMLDocument">XMLDocument
1.0a1</A> - Zope 2.0x product for formatting, querying and manipulating
XML documents.  (22-Jul-99)

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From oli@andrich.net  Tue Jul 27 16:19:43 1999
From: oli@andrich.net (Oliver Andrich)
Date: Tue, 27 Jul 99 15:19:43 GMT
Subject: Python4linux -- Mailing list for discussing issues with the Python distribution for Linux and Python on Linux in general.
Message-ID: <mt2.0-21715-933088783@news.informatik.uni-bonn.de>

Hi,

I like to announce the creation of a new mailing list on starship.skyport.net
which was setup to discuss the following topics:

    - The problems with the Python distribution for RPM based Linux systems
      (glibc 2.x Systems only)
    - The problems with Python on Linux in general. I know that this can be
      discussed in the newsgroup too, but I think that some people like to
      discuss some very specific things on a low volumen list.
    - The future of the Python distribution for Linux systems. Currently the whole
      project is run, administrated and maintained by myself with some very
      helpful contributors and users. But I like to move the whole thing to
      a group effort, where I see myself as one contributor to this effort
      who also tries to coordinate and maintain the whole effort
    - Discussion of new Linux platforms where we like to port Python too. And
      all this stuff.
    - I also like to focus the verious efforts to package Python stuff for
      Linux in one way. So that we can offer one location where Linux users
      interested in prepackaged stuff can go to and fetch what they want.
      The whole thing shouldn't be a "Oliver Andrich did it." show or so,
      but I want to spread Python as Perl has spread. And
      starship.python.net and python.org do a very good job. And we can
      supply an extra service for Linux users.

I hope a lot of people will subscribe to this list and that we can
coordinate the effort in a better way. And my personal mailbox get's a
little bit smaller. Don't read this as "go away, I am to busy." but I think
the whole project is way to big so that I can maintain it alone. ;-))))

Best regards, 

    Oliver Andrich

<P><A HREF="http://starship.python.net/mailman/listinfo/python4linux">
Python4Linux mailing list</A> - mailing list for discussing issues with
the Python distribution for Linux and Python on Linux in
general.  (23-Jul-99)

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From Fred L. Drake, Jr." <fdrake@acm.org  Tue Jul 27 16:20:32 1999
From: Fred L. Drake, Jr." <fdrake@acm.org (Fred L. Drake)
Date: Tue, 27 Jul 99 15:20:32 GMT
Subject: Python documentation available as ZIP files
Message-ID: <mt2.0-21715-933088832@news.informatik.uni-bonn.de>

I've received enough hostile mail from Windows users not
understanding how to unpack .tgz archives (er, WinZip works for me...)
that I will be making most of the documentation packages available as
ZIP archives as well as .tgz archives.

  For the most part, the ZIP archives are approximately the same size
as the .tgz archives, but be aware that, even with maximal
compression, the HTML ZIP archive is substantially larger than the
.tgz equivalent.  This is likely caused by the ZIP format having two
directory entries for each file instead of one; with a lot of small
files, this can make a difference.

  The new files are now available on the master FTP and Web sites at
python.org; they should appear on mirrors over the coming week.


  -Fred

== 
Fred L. Drake, Jr.	     <fdrake@acm.org>
Corporation for National Research Initiatives

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From skaller@maxtal.com.au  Tue Jul 27 16:22:31 1999
From: skaller@maxtal.com.au (John MaxSkaller)
Date: Tue, 27 Jul 99 15:22:31 GMT
Subject: unicode data tables
Message-ID: <mt2.0-21715-933088951@news.informatik.uni-bonn.de>

I have posted the unicode (and other) encoding subdocument of
interscript v1.0a9 to the Web. At

	http://www.xenon.triode.net.au/~skaller/unicode/index.html

you will find documented Python source for conversion of various character
sets, including ISO-8859-X, Wansung, Johab, GB, Big5, ShiftJis, and various
Microsoft/IBM proprietary code pages.

The document contains a character by character description of the Unicode
subset of ISO-10646, routines for converting UCS-2, USC2le, UCS-4, UCS4-le
to UTF-8 (the native encoding used by interscript), and compact tables of all
the glyphs (for unicode and each of the foreign character sets).

If you're interested in internationalisation, you may find this web useful.
You can browse online, or download it as a tarball (using http).
You will need a browser with appropiate fonts to see Chinese, Japanese,
Korean, Arabic and other glyphs.

[Note: the table of contents uses a folding tree under MSIE4-5, it
takes some time for my ECMA script to process the table. It's not
broken, just slow!]


John Max Skaller                ph:61-2-96600850              
mailto:skaller@maxtal.com.au       10/1 Toxteth Rd 
http://www.maxtal.com.au/~skaller  Glebe 2037 NSW AUSTRALIA

<P><A HREF="http://www.xenon.triode.net.au/~skaller/unicode/index.html">
unicode data tables</A> - documented Python source for conversion of
various character sets, including ISO-8859-X, Wansung, Johab, GB, Big5,
ShiftJis, and various Microsoft/IBM proprietary code pages.  (25-Jul-99)

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From gmcm@hypernet.com  Tue Jul 27 16:23:14 1999
From: gmcm@hypernet.com (Gordon McMillan)
Date: Tue, 27 Jul 99 15:23:14 GMT
Subject: Win32 Installer - new release
Message-ID: <mt2.0-21715-933088994@news.informatik.uni-bonn.de>

A new release (01a) of the Win32 Installer package is available on
starship:

 http://starship.python.net/crew/gmcm/install.html

This release incorporates bug fixes and some enhancements from (and 
inspired by) Robin Dunn.

 - A generated install script is now "safe"
 - File atimes, mtimes copied if possible
 - Install packages can be built from any directory
 - Ability to gather all dependencies in a directory, so you can use 
   WinZip or WIse or whatever to distribute the results.

What is it?
 Briefly, it is a sort of compilerless Freeze - a way of distributing 
Python apps with all the required Python support included.

 Python-style license.

Contact: gmcm@hypernet.com

<P><A HREF="http://starship.python.net/crew/gmcm/install.html">Win32
Installer release 01a</A> - a compiler-less way of distributing Python
apps on Windows.  (25-Jul-99)

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From hinsen@cnrs-orleans.fr  Tue Jul 27 16:25:06 1999
From: hinsen@cnrs-orleans.fr (Konrad Hinsen)
Date: Tue, 27 Jul 99 15:25:06 GMT
Subject: ScientificPython 2.0b1
Message-ID: <mt2.0-21715-933089105@news.informatik.uni-bonn.de>

The first public beta release of ScientificPython 2.0 is now available
from
       http://starship.python.net/crew/hinsen/scientific.html
and
       http://dirac.cnrs-orleans.fr/programs/scientific.html

This is a completely revised release and *not* compatible with earlier
releases. The major difference is the introduction of a package
structure; all modules are now submodules of the top-level module
Scientific. Version 2 also includes the netCDF interface module, which
was previously in a separate distribution. Another important new
feature is full documentation :-)

Following established traditions in the Python community, I will be
on vacation for three weeks from Wednesday. Please take your time
to fix any bugs before reporting them to me ;-)

== 
-------------------------------------------------------------------------------
Konrad Hinsen                            | E-Mail: hinsen@cnrs-orleans.fr
Centre de Biophysique Moleculaire (CNRS) | Tel.: +33-2.38.25.55.69
Rue Charles Sadron                       | Fax:  +33-2.38.63.15.17
45071 Orleans Cedex 2                    | Deutsch/Esperanto/English/
France                                   | Nederlands/Francais
-------------------------------------------------------------------------------

<P><A HREF="http://starship.skyport.net/crew/hinsen/scientific.html">
ScientificPython 2.0</A> - Konrad Hinsen's collection of scientific/math
modules; now includes netCDF module and full documentation.  (26-Jul-99)

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From wolfgang.grafen@de.bosch.com  Tue Jul 27 16:27:20 1999
From: wolfgang.grafen@de.bosch.com (Wolfgang Grafen)
Date: Tue, 27 Jul 99 15:27:20 GMT
Subject: seqdict 0.0 - 2 sequential dictionary emulations
Message-ID: <mt2.0-21715-933089240@news.informatik.uni-bonn.de>

26.7.1999 

http://www.germany.net/teilnehmer/100,366919/Python/Modules/Modules.html

Package seqdict
Module seqdict version 0.0
Module mseqdict version 0.0 
================================================

seqdict - single value dictionary 
msedict - multiple value dictionary 

The Python built-in dictionary has no reliable sequence order because
of performance reasons. 

The two new dictionaries introduced here keep their entries in sequence. 

* seqdict keeps one value for one key 
* mseqdict keeps multiple values per key and is the closest emulation 
  of areal world dictionary. 

As the sequential dictionary is a combination of a list and a dictionary
you can do most operations defined with lists as well and much more. 

Now you can slice, add, sort with dictionaries. The functional operations
map, filter, reduce are implemented as well. Use a dictionary like a stack
with push and pop. Split it, reverse it and swap keys and values.

A small tutorial is provided as HTML and Postscript Source and is
subject to become improved some other day. 

I think both dictionaries are candidates for the python standard
library. 

Use the seqdicts to emulate a printed dictionary. Use them for
csv-tables. 
Keep parsed code in a seqdict, modify it and write it back ... 

Download from 
http://www.germany.net/teilnehmer/100,366919/Python/Modules/Modules.html

Wolfgang Grafen 
mailto:WolfgangGrafen@gmx.de

For the web thingy:
<P><A HREF="http://www.germany.net/teilnehmer/100,366919/Python/Modules/Modules.html">seqdict
0.0</A> - package with two sequential dictionary emulations.  (26-Jul-99)

Wolfgang Grafen 
mailto:WolfgangGrafen@gmx.de

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From kernr@mail.ncifcrf.gov  Tue Jul 27 16:27:58 1999
From: kernr@mail.ncifcrf.gov (Robert Kern)
Date: Tue, 27 Jul 99 15:27:58 GMT
Subject: Updated compile tools for egcs/mingw32
Message-ID: <mt2.0-21715-933089278@news.informatik.uni-bonn.de>

Hello all,

compmgw.py and makemgw.py are Python scripts that ease the compilation
of Python extensions on Win32 using the free egcs 1.1.2 compiler on
the i386-mingw32 target.

compmgw.py processes a Setup file and generates a Makefile that will
compile your extension.

makemgw.py processes a Setup file but runs the compiler commands
itself and bypasses the Makefile.  It uses a very simple (and probably
inefficient and wrong) dependancy checker to generate the list of
commands to run.

WARNING: The code in both of these modules is incredibly bad.  "hacks
upon hacks upon hacks" sums up the state of these scripts pretty well.
Do not read them if you have a heart condition.  *Please* don't use
them for anything else.  Instead join the distutils-SIG and work with
them to create a general mechanism.

Both of these scripts will be dropped unceremoniously once the
distutils-SIG gets far enough in its work.

The scripts are available separately:
  * http://starship.python.net/crew/kernr/mingw32/compmgw.py
  * http://starship.python.net/crew/kernr/mingw32/makemgw.py

or together with other tools:
  * http://starship.python.net/crew/kernr/mingw32/Py-mingw32-tools.zip

Robert Kern

<P><A HREF="http://starship.python.net/crew/kernr/mingw32/Notes.html">
Updated compile tools for egcs/mingw32</A> - updated scripts to parse
Setup files for compiling on Win32 systems with egcs/mingw32.  (27-Jul-99)

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From fleck@informatik.uni-bonn.de  Tue Jul 27 16:39:03 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Tue, 27 Jul 99 15:39:03 GMT
Subject: [fm] Zope 2.0.0b1
Message-ID: <mt2.0-22000-933089942@news.informatik.uni-bonn.de>

  Zope 2.0.0b1
  amos - July 25th 1999, 14:50 EST

  Zope is a free, Open Source web application platform used for building
  high-performance, dynamic web sites. It contains a powerful and simple
  scripting object model and high-performance, integrated object
  database.

  Changes: Major changes include: ZODB 3, the next generation of the Zope
  Object Database, Z Classes, a new mechanism for building Zope
  applications, WebDAV support, and ZServer, the integration of Zope and
  Medusa.

   Download:http://www.zope.org/Download/
   Homepage:http://www.zope.org/

  Changelog:http://www.zope.org/Download/Releases/Zope-2.0.0b1/CHANGES.txt

                  Author: Digital Creations
                 License: OpenSource
                Category: Web/Development

  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.zope.org/">Zope 2.0.0b1</A> - Zope is a free, open
source web application platform used for building high-performance,
dynamic web sites.  (25-Jul-99)

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From fleck@informatik.uni-bonn.de  Tue Jul 27 16:44:39 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Tue, 27 Jul 99 15:44:39 GMT
Subject: [fm] FXPy 0.99.55
Message-ID: <mt2.0-22000-933090278@news.informatik.uni-bonn.de>

  FXPy 0.99.55
  Lyle Johnson - July 22nd 1999, 04:06 EST

  FXPy is a Python extension module which provides an interface to the
  FOX cross-platform GUI library. With a few minor exceptions, FXPy
  provides a complete interface to FOX. FOX is a C++-based toolkit for
  developing graphical user interfaces easily and effectively, and it
  runs natively under both Unix/X and Microsoft Windows. Some of the
  significant features of FOX include a rich set of widgets, powerful but
  easy-to-use layout managers, extensive support for 3-D modeling using
  OpenGL or Mesa, drag-and-drop (using the XDND protocol) and a registry
  for persistent application settings.

  Changes: This is the first official announcement.

      Download:ftp://ftp.cfdrc.com/pub/FOX/FXPy-0.99.55.tar.gz
      Homepage:http://www.airnet.net/ljohnson/FXPy/

                  Author: Lyle Johnson
                 License: LGPL
                Category: Development/Python Modules
              Depends on: Python, FOX (and optionally PyOpenGL)

  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.airnet.net/ljohnson/FXPy/">FXPy 0.99.55</A> - Python
interface to the FOX free cross-platform C++ graphical user interface library
for Unix/X11 and Microsoft Windows.  (22-Jul-99)

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From M.Wise@ccsr.cam.ac.uk  Wed Jul 28 19:13:37 1999
From: M.Wise@ccsr.cam.ac.uk (Michael Wise)
Date: Wed, 28 Jul 99 18:13:37 GMT
Subject: Agrepy 1.0: Python port of agrep string matching with errors
Message-ID: <mt2.0-16224-933185617@news.informatik.uni-bonn.de>

<A HREF="http://glimpse.cs.arizona.edu/software.html">agrep</A> is a suite
of command-line (i.e. UNIX user level) string matching functions, written by
Sun Wu and Udi Manber (described in "Fast Text Searching Allowing Errors",
CACM, 35(10), 1992).

While the majority of the functionality is already found in Python, the
ability to perform string searches accepting a limited number of errors has
not been available till now.

Such searches are able to deal, for example, with spelling errors, or the
differences between North American and British English. Alternatively, this
form of string matching is able to model the attachment of a primer to a
target DNA sequence (i.e. attachment occurs if there are no more than, say,
2 indels).

<P><A HREF="http://www.ccsr.cam.ac.uk/~michaelw/pyagrep.html">agrepy
1.0</A> - Python interface to the 
<A HREF="http://glimpse.cs.arizona.edu/software.html">agrep</A>
approximate string matching implementation.  (27-Jul-99)

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From dsnider@mindspring.com  Wed Jul 28 19:17:21 1999
From: dsnider@mindspring.com (Dan Snider)
Date: Wed, 28 Jul 99 18:17:21 GMT
Subject: COMMERCIAL: ObjectDomain 2.5 (UML modeling tool)
Message-ID: <mt2.0-16224-933185841@news.informatik.uni-bonn.de>

The final release of ObjectDomain 2.5 is now available! See download
information below.

Object Domain Systems unveils ObjectDomain 2.5, the latest version of our
flagship UML modeling tool. Implemented in pure Java, ObjectDomain provides
a scalable, multi-platform, user extendable CASE tool that redefines the
expectations of object modeling software.

NEW FEATURES:

  - Support for all nine UML diagrams backed by a true UML meta-model
  - Better performance with smaller memory footprint
  - Version control and multi-user support via file-based repository
  - HTML documentation and glossary generation for user models
  - Advanced model searching with regular expression support
  - Full round-trip for Java
  - Various UI enhancements

  Note: Some features may not be available in the standard edition.

FEATURES PREVIOUSLY INCLUDED:

  - Code generation and reverse engineering for Java, C++, and Python
  - Powerful diagramming with auto-layout, bezier curves, color support,
    stereotype icons, and extensive control of presentation aspects using
    "styles"
  - Intuitive user interface with switchable look-and-feel and theme
    support. Open architecture allows additional language support, user
    customization and third-party add-ins
  - Python scripting support with integrated command console
  - Interface features include multi-perspective browsing, unlimited
    undo/redo, and a diagram thumbnail view that allows panning and zooming

QUANTITY DISCOUNTS

  In addition to our standard quantity discount, we are also offering a
  special discount or the purchase of multiple copies. For further
  information call 919-461-4904.

OBJECTDOMAIN 2.6 WILL BE A FREE UPGRADE!

  Although the exact feature set is not finalized, we have committed to
  providing 2.6 as a FREE upgrade to 2.5. Features we plan for 2.6 include:

  - Round trip engineering for C++ (currently have round trip
    engineering for Java)
  - Full import/export Rational Rose model files
  - Support for Java 2 (previously known as Java 1.2)
  - Enhanced printing
  - Updated alignment UML 1.3
  - Various UI enhancements
  - IDL generation

------------------------------------------------------------------------

Learn more about ObjectDomain 2.5:

  http://www.objectdomain.com/domain

Download ObjectDomain 2.5:

  http://www.objectdomain.com/odEvalUser


The ObjectDomain Development Team

Object Domain Systems Inc.
support@objectdomain.com
http://www.objectdomain.com

<P><A HREF="http://www.objectdomain.com">ObjectDomain 2.5</A> -
commercial UML modeling tool with Python scripting support.  (27-Jul-99)

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From mmuller@enduden.com  Wed Jul 28 19:19:38 1999
From: mmuller@enduden.com (Michael Muller)
Date: Wed, 28 Jul 99 18:19:38 GMT
Subject: PyESD - Python Wrapper for EsounD library
Message-ID: <mt2.0-16224-933185978@news.informatik.uni-bonn.de>

PyESD is a SWIGged wrapper around the Enlightenment Sound Daemon client
library with some additional classes to provide a more object-oriented
interface.

URL:     http://www.users.cloud9.net/~proteus/pyesd/
Contact: proteus@cloud9.net
License: Variation on BSD, free for commercial and non-commercial use

=============================================================================
michaelMuller = proteus@cloud9.net | http://www.cloud9.net/~proteus
-----------------------------------------------------------------------------
We are explorers in the further reaches of experience: demons to some, angels
to others.  - "Pinhead" from "Hellraiser"
=============================================================================

<P><A HREF="http://www.users.cloud9.net/~proteus/pyesd/">PyESD</A> - Python
interface to the Enlightenment Sound Daemon client library for UNIX.  (27-Jul-99)

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From gherman@my-deja.com  Wed Jul 28 19:20:45 1999
From: gherman@my-deja.com (Dinu C. Gherman)
Date: Wed, 28 Jul 99 18:20:45 GMT
Subject: codeplot
Message-ID: <mt2.0-16224-933186045@news.informatik.uni-bonn.de>

Codeplot

This is something like a toy example for Piddle that you might
use as well to visually fingerprint Python code in a weird way,
a bit like in the "Matrix", perhaps. ;-)


Introduction (from codeplot's doc string):

This module takes a Python source code file and creates
a two-dimensional plot out of it. The plot generated is
a symmetrical one, much like a 2D matrix where a dot at
(i,j) indicates that lines i and j in the input file are
the same.

Sounds silly? Maybe, yes. After all, this is a one day
fun 'project' while reading a book on, you guessed it,
patterns. But I guess you'll be surprised of what you can
see in these silly plots.

Peaks result by definition from identical lines (in red).
Very often this will be the case due to empty lines,
therefore these lines are marked distinctly (grey). Other
interesting things come from lines that are similar, but
not identical. In the current implementation, "similar"
means lines that are identical modulo an arbitrary inden-
tation (marked in blue). So this is a little bit only of
a bias towards Python as a language, but in fact you can
run codeplot on any kind of ASCII file (that is made of
individual lines, separated by newlines).

The plots are generated using the new PIDDLE interface
(during development codeplot created PDF files) in the
version 1.0.3. Some words of praise for PIDDLE: it's
cool! Without it codeplot would never have happened.

What's the future of this thing?! I don't know! I'll do
a bit more here and there, maybe create a proper EPS
file instead of PDF (such that it can be included some-
where else more easily). There's likely still something
to improve to handle indentation by tabs properly as
well. It could be faster, perhaps, but it's inherently
O(n^2), so don't use it on a 200 KB C file (yes - they
DO exist, sigh...). Using Numeric might be an idea, not
sure... If you think you can do something to improve it
let me know. If you use it in some interesting way, let
me know, too.


Installation:

Put codeplot.py somewhere in your Python path. Also make sure
you have Piddle already installed. You can find Piddle here:
http://www.strout.net/python/piddle/


Files:

README.txt  - This file.
codeplot.py - The Python codeplot module.
samples.zip - Some sample PDF files.

The samples were more or less randomly selected from the following
packages: pythondoc, idle, pdfgen, piddle, consdiag, Zope, the Python
Interpreter (a C file) and codeplot itself (the filenames should
suffice to get an idea of where they awere taken from). The original
python files are not included, though (except codeplot.py). Several
differences can be observed, but these are to be explained elsewhere.


Contact:

Author:   Dinu C. Gherman, gherman@europemail.com.nospam
Web-Site: http://starship.python.net/crew/gherman/playground/codeplot/


Copyright:

Do with it whatever you want, but don't sue me! If you make money
with codeplot, pay me half of it as royalities! ;-)


1999-07-28 (codeplot 0.1)


Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

<P><A HREF="http://starship.python.net/crew/gherman/playground/codeplot/">codeplot
0.1</A> - visually fingerprint Python code in a weird way...  (28-Jul-99)

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From Amos@digicool.com  Wed Jul 28 21:32:29 1999
From: Amos@digicool.com (Amos Latteier)
Date: Wed, 28 Jul 99 20:32:29 GMT
Subject: Zope Weekly News - Wed, 28 Jul 1999
Message-ID: <mt2.0-17381-933193949@news.informatik.uni-bonn.de>

Hello,

The big news this week was the release of Zope 2.0 beta one. Zope 2
final is getting closer and closer. Beta one increases stability over
the alpha releases and also adds a few missing pieces like the ability
to tie permissions to factories. Also you can now export Zope objects to
XML. Speaking of XML, as of beta one all basic Zope objects support a
subset of the DOM Element interface, and the unsupported XML Document
product is out and in CVS.

  * Zope 2.0 beta one was released this week. Now you can download a
binary release of Zope 2.
  
  http://www.zope.org/Download/Releases/Zope-2.0.0b1
  
  * The Zope site received a look and feel makeover. Most people seem to
like the new design. A couple people posted describing the strange
feeling of having the entire site change while browsing it. Zope
sessions are cool!
  
  http://www.zope.org/pipermail/zope/1999-July/007368.html
  
  * Amos Latteier announced the availability of XML Document 1.0a1 a
Zope product for using XML. A couple days later, XML Document made it
into public CVS.
  
  http://www.zope.org/pipermail/zope/1999-July/007126.html
  http://www.zope.org/Download/XMLDocument
  http://www.zope.org/pipermail/zope-dev/1999-July/000990.html
	
  * Anthony Pfrunder announced a new version of his Zope for windows
distribution.
  
  http://www.zope.org/pipermail/zope/1999-July/007189.html
	
  * Michel Pelletier announced Zippy Tag which allows you to insert
random Zippy the Pinhead quotes in your Zope documents. Yes!
  
  http://www.zope.org/pipermail/zope/1999-July/007190.html
  http://www.zope.org/Download/Contrib/Zippy.tgz
  
  * Paul Everitt discusses how you can now export Zope objects to XML.
Basically the XML format describes Python pickles.
  
  http://www.zope.org/pipermail/zope/1999-July/007200.html
  
  * Michel Pelletier posted an extremely simple summary of how to hook a
form to a database. This is a good read for those new to Zope.
  
  http://www.zope.org/pipermail/zope/1999-July/007336.html
  
  * Andreas Kostyrka posted a patch to allow Zope to server multiple
sites from one process. Very interesting, multiple sites from one object
database!
  
  http://www.zope.org/pipermail/zope-dev/1999-July/000931.html
  http://www.mtg.co.at/projects/subhosting/
  
  * Eric Kidd posted a Zope/XML-RPC todo list. Follow up posts confirmed
that a number of the items have already been done.
  
  http://www.zope.org/pipermail/zope-dev/1999-July/000972.html
  
  * Brian Lloyd posted an insightful message describing the 'Owner' role
and how to use proxy roles to allow limited access to restricted
functions.
  
  http://www.zope.org/pipermail/zope-dev/1999-July/000987.html
  
  * Chris Petrilli mentioned that Gadfly is finally being updated to the
latest version. Alright!
  
  http://www.zope.org/pipermail/zope-dev/1999-July/001002.html
  

See you next week, same time, same channel.

-Amos

== 
Amos Latteier         mailto:amos@digicool.com
Digital Creations     http://www.digicool.com

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From mal@lemburg.com  Fri Jul 30 15:26:34 1999
From: mal@lemburg.com (M.-A. Lemburg)
Date: Fri, 30 Jul 99 14:26:34 GMT
Subject: mxTextTools Package - Version 1.1.0
Message-ID: <mt2.0-24150-933344794@news.informatik.uni-bonn.de>

ANNOUNCING:

                   mxTextTools Version 1.1.0

          A Python extension package providing fast text
                 scanning and processing tools


WHAT IT IS:

mxTextTools is an extension package for Python that provides 
* a fast text search type (using a modified Boyer-Moore algorithm)
* a finite state machine for marking and analysing text
  (the Tagging Engine)
* a set of specialized text processing functions
* a set of functions that work with character sets

Applications include parsing structured text, finding and extracting
text (either exact or using translation tables) and recombining
strings to form new text. Everything was implemented having high
performance in mind.

WHAT'S NEW ?

The 1.1.0 release adds several new text processing functions to
the already large set: splitlines(), countlines(), suffix(), prefix(),
str2hex() and hex2str(). Many existing functions/objects were
enhanced to work in a more general context.

All the details are available at:

        http://starship.skyport.net/~lemburg/mxTextTools.html#History

This release also includes a precompiled Windows DLL so that you can
use the package right away. Installing on that platform boils down
to a simple unzip in the \Python\Lib directory.

WHERE CAN I GET IT ?

The full documentation and instructions for downloading and installing
can be found at:

        http://starship.skyport.net/~lemburg/mxTextTools.html

WHAT DOES IT COST ?

It comes with a Python-type license, but is free otherwise.

WHERE CAN I GET SUPPORT ?

I am offering commercial support for this package through
Python Professional Services Inc. (http://www.pythonpros.com).
Look on their support pages for details or contact me directly.

REFERENCE:

<P><A HREF="http://starship.skyport.net/~lemburg/mxTextTools.html>
mxTextTools 1.1.0</A> - fast text processing tools.  (29-Jul-99)

== 
Marc-Andre Lemburg
______________________________________________________________________
Y2000:                                                   155 days left
Business:                                      http://www.lemburg.com/
Python Pages:                           http://www.lemburg.com/python/

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From jonathan@onegoodidea.com  Fri Jul 30 15:31:00 1999
From: jonathan@onegoodidea.com (Jonathan Hogg)
Date: Fri, 30 Jul 99 14:31:00 GMT
Subject: RTSP streaming media proxy
Message-ID: <mt2.0-24150-933345060@news.informatik.uni-bonn.de>

hot on the heels of my last post, here is my next contribution. again,
it can be found on the projects page of our company web-site:

   <http://www.onegoodidea.com/projectscore.html>

RTSP_Proxy is a proxy server for the RTSP/RTP streaming media protocols.
this is a quick-and-dirty hack i threw together a couple of weekends ago
in order to be able to watch the MacWorld keynote address which was
netcast using QuickTime 4 video/audio streaming.

for information on QuickTime 4, take a look at:

   <http://www.apple.com/quicktime/>

unfortunately, whilst apple chose a non-proprietry standard protocol for
implementing their streaming architecture, they also chose one which is
not particularly established and is not IP masquerading friendly. apple
provide a proxy server for running on a firewall/NAT machine, but it's
pretty flaky so i had a stab at writing my own.

i've only run it on an i386 linux box, but i've been told it works on
freebsd too. it requires threads and sockets, but should work on anything
that provides them.

it's not a pretty program, but it worked enough for me to watch the new
iBook being launched :-)  i'm in the process of writing a new version, but
thought this might be of interest/amusement.

again, all comments welcome,

:-j

== 
jonathan hogg, one good idea limited, 25 clouston street, glasgow g20 8qr, uk
jonathan@onegoodidea.com www.onegoodidea.com t:(0)976-614338 f:(0)7970-537451

<P><A HREF="http://www.onegoodidea.com/projectscore.html">RTSP proxy</A> -
quick-and-dirty proxy server for the RTSP/RTP streaming media protocols,
written in Python.  (29-Jul-99)

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From jonathan@onegoodidea.com  Fri Jul 30 15:33:21 1999
From: jonathan@onegoodidea.com (Jonathan Hogg)
Date: Fri, 30 Jul 99 14:33:21 GMT
Subject: Python/PostgreSQL interface module
Message-ID: <mt2.0-24150-933345201@news.informatik.uni-bonn.de>

well after much lurking and occasional commenting on these groups, here is
my first contribution to the community. it's a module for accessing PostgreSQL
databases from Python.

yes, i know there already is one, but i wanted to play with some different
features and to get the hang of writing extension modules. you are free to not
use this module. please don't email me to tell me i've wasted my time - all
learning is worthwhile and maybe someone else will get something useful from
this.

i'm afraid it doesn't have a proper name yet because i can't think of one - a
free copy of the source for the best idea ;-)

i welcome feedback,

:-j



(extracted from the README:)


Python/PostgreSQL Interface Module                         (Version: 1.0)
----------------------------------


Summary:
--------

PostgreSQL is a neat, free, relational database system which can be found at:

   <http://www.postgresql.org/>

This is a module that provides the PostgreSQL programmers' API to Python
programmers. It is written in C and compiles down to a shared-object file
that can be dynamically loaded into the Python interpreter. It is basically
a wrapper around the 'libpq' library that comes with PostgreSQL.


Limitations:
------------

This interface has not been used in anger yet. It's been written as part of
a one good idea project and I'm releasing it more widely because it may be
of use to other people and might result in some useful feedback.


License:
--------

There should be a LICENSE file accompanying this distribution (and at the top
of each source file). I've used the Berkeley license because I've always
liked it. This code is not copylefted, feel free to stick it into a commercial
product and sell it, become rich, buy a small island in the pacific, retire
young and happy. However, you have to retain the copyright on the code, and
it would be polite to send me a note of thanks ;-)


Obtaining The Latest Distribution:
----------------------------------

You should be able to find it by following the obvious links on the one good
idea webpages for 'Projects':

   <http://www.onegoodidea.com/>

As of this distribution, the appropriate URL was:

   <http://www.onegoodidea.com/downloads/python-postgresql-1.0.tgz>


PyGreSQL
--------

This module is not PyGreSQL. PyGreSQL is written by D'Arcy J.M. Cain,
<darcy@druid.net>. It is another Python/PostgreSQL interface which has been
around longer than this one. I wrote this module because I wanted a different
mechanism for accessing named fields in query results (and partly as an
exercise in extending Python).

== 
jonathan hogg, one good idea limited, 25 clouston street, glasgow g20 8qr, uk
jonathan@onegoodidea.com www.onegoodidea.com t:(0)976-614338 f:(0)7970-537451

<P><A HREF="http://www.onegoodidea.com/projects.html">Python/PostgreSQL
API</A> - access PostgreSQL programmers' API from Python.  (29-Jul-99)

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From bwarsaw@cnri.reston.va.us (Barry A. Warsaw)  Sat Jul 31 00:40:51 1999
From: bwarsaw@cnri.reston.va.us (Barry A. Warsaw) (Barry A. Warsaw)
Date: Fri, 30 Jul 99 23:40:51 GMT
Subject: Wash. D.C. Area: DCPIGgies Get Together
Message-ID: <mt2.0-26154-933378051@news.informatik.uni-bonn.de>

Notice to all Washington DC area Python users:

We are pleased to be resurrecting the DC area Python interest group
meetings, now called DCPIGgies.  We will be having our first meeting
at CNRI in Reston, Virginia on Tuesday August 31, 1999 from 7:30pm to
9:30pm.  The aim is to keep this meeting pretty technical.

To that goal, we're going to have two exciting presentations.  For the
first hour, the Digital Creations guys will be giving a talk on Zope
2.0's unique object model (acquisition, run-time classes,
transactional objects, etc.) including how Python programmers might
use this in their own non-Zope projects.

In the second hour, Andrew Kuchling will be talking about something
XML-ish, probably processing the Open Directory Project's
(www.dmoz.org) RDF dumps.

There will be question and answer periods after each talk, and we may
have an "open phones" going later than 9:30 if there's interest and if
Guido or I am still awake. :)

Pizza, salad, and soda will be provided.  We are asking for a
voluntary $5 donation at the door to cover the costs of food.  It is
very important that you RSVP by email to bwarsaw@cnri.reston.va.us so
that I can get an accurate head count (otherwise you may go hungry!).
We also need to make sure that we can fit everyone into our conference
room, so let me know if you're coming, even if you aren't going to
eat.

Directions to CNRI can be found on the Web:

    http://www.cnri.reston.va.us/directions.html

See you then!
-Barry

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From bwarsaw@cnri.reston.va.us (Barry A. Warsaw)  Sat Jul 31 00:43:42 1999
From: bwarsaw@cnri.reston.va.us (Barry A. Warsaw) (Barry A. Warsaw)
Date: Fri, 30 Jul 99 23:43:42 GMT
Subject: Mailman 1.0
Message-ID: <mt2.0-26154-933378222@news.informatik.uni-bonn.de>

On behalf of the rest of the Mailman Cabal, I'm very happy (and
somewhat relieved) to announce the release of Mailman 1.0.  I've just
uploaded the tarball to www.list.org so follow the links there to
download it.

Mailman -- the GNU Mailing List Manager -- is software to help manage
email discussion lists, much like Majordomo and Smartmail. Unlike most
similar products, Mailman gives each mailing list a web page, and
allows users to subscribe, unsubscribe, etc. over the web. Even the
list manager can administer his or her list entirely from the
web. Mailman also integrates most things people want to do with
mailing lists, including archiving, mail-to-news gateways, and so on.

Mailman is written almost completely in Python (there's a little bit
of C for security purposes).  Mailman is distributed under the terms
of the GPL.

>From the NEWS file, here are the list of changes since 1.0rc3:

- Configure script now allows $PREFIX (by default /home/mailman) to be 
  permissions 02755.  Also, configure now tests for vsnprintf()

- Workaround, taken from GNU screen, for systems missing vsnprintf()

- Return-Receipt-To: and Disposition-Notification-To: headers are
  always removed from posted messages (they can be used to troll for
  list membership).

- Workaround for MSIE4.01 (and possibly other versions) bug in the
  handling of cookies.

- A small collection of other bug fixes.

Enjoy,
-Barry

<P><A HREF="http://www.list.org/">Mailman 1.0</A> - the GNU Mailing
List Manager, written in Python; features a web-based subscription
and list maintenance interface.  (30-Jul-99)

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From samschul@pacbell.net  Sat Jul 31 05:15:32 1999
From: samschul@pacbell.net (Sam Schulenburg)
Date: Sat, 31 Jul 99 04:15:32 GMT
Subject: A Python SCSI hard drive development environment for Windows95/98/NT
Message-ID: <mt2.0-27640-933394532@news.informatik.uni-bonn.de>

ASPYPython is a environment for the testing and development of SCSI hard
drives. Using Guido van Rossum's IDLE environment allows for the rapid
development of test scripts that can be used in the evaluation and testing
of SCSI hard drives using the ASPI (Advanced SCSI Programming Interface)
that is available under Windows 95/98/NT.

The low level SCSI interface functions are incorporated in a DLL
(ASPIPy.dll) that behaves like a traffic cop between the user and the hard
drive. all commands from the user are sent from Python to the dll, and all
drive responses are sent from the dll to either the log file, the user via
Python, or both.  Higher level scripts and error messages are provided by
ASPI.py. This file contains all the startup and initializing function needed
by the DLL.

Some of the following features are provided by the DLL,and ASPI.py

1) Six byte, Ten byte, and Twelve byte commands are supported with
   io6(),io10(),and io12() functions that take either hex or decimal
   parameters i.e Inquiry command would be
   io6(0x12,0x00,0x00,0x00,0xff,0x00) or io6(18,0,0,0,255,0).

2) Sensekey and Sensecode values are translated to English statements for
   the user.  i.e 0x06,0x29,0x00 would be displayed as 'Unit Attention ',
   'Power On Reset, Or Bus Device Reset Occurred '

3) Added help has been placed in the help menu under IDLE this help contains
   the folling items:
     a) Help for ASPIPython. All functions are documented here and in
        documentation string within each function
     b) Help of Python itself. A link is provided to a public domain
        browser that brings up the Python Documentation
     c) A makedocs link that allows users to add their own help messages to
        their scripts (See Documentation)

4) All of the advantages of Python for rapid modification and development of
   test scripts

5) Sample script files that demonstrate the use of these libraries.

For further information see the Documentation at
http://starship.python.net/crew/schulenburg

<P><A HREF="http://starship.python.net/crew/schulenburg/">ASPIPython</A> -
an ACPI/SCSI hard drive development environment for
Windows95/98/NT.  (30-Jul-99)

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From fleck@informatik.uni-bonn.de  Sat Jul 31 06:26:19 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Sat, 31 Jul 99 05:26:19 GMT
Subject: [fm] Pagecast 1.1.0
Message-ID: <mt2.0-28810-933398779@news.informatik.uni-bonn.de>

  Pagecast
  Preston Landers - July 01st 1999, 20:27 EST

  Pagecast submits lists of URL's to various search engines such as
  AltaVista, Infoseek, Excite, Google, etc to be indexed. It can run from
  the command-line or as a mail-robot (email a list of URL's to
  pagecast@yourmachine). It has a few advanced features such as the
  ability to rate a URL's keyword-to-title relevance and fix broken meta
  tags. Pagecast requires Python (with threading.)

   Download: http://askpreston.com/projects/pagecast/pagecast-1.1.0.tar.gz
   Homepage: http://askpreston.com/projects/pagecast/index.html
  Changelog: http://askpreston.com/projects/pagecast/ChangeLog.txt

          Stable Version: 1.1.0
                  Author: Preston Landers
                 License: GPL
                Category: Web/Tools
              Depends on: Python
             Appindex ID: 930875279

          Announcements
            * Pagecast 1.1.0 - by Preston Landers on July 28th 1999, 05:12
            * Pagecast 1.0.1 - by Preston Landers on July 05th 1999, 12:07
            * Pagecast 1.0 - by Preston Landers on July 02nd 1999, 17:14

  Comments:

  new mailing list for Pagecast
  Preston Landers - July 06th 1999, 23:06 EST
  Visit the Pagecast home page (listed above) for information about
  joining the new Pagecast mailing list.

  Possible incompatibility
  Preston Landers - July 15th 1999, 19:12 EST
  Some users are reporting problems with Pagecast and other Python
  software when they are running both the newest Python 1.5.2 *and* the
  Linux Kernel version 2.0.x.

  The solution pending further debugging is to either upgrade to Linux
  2.2.x or downgrade Python to 1.5.1.

  
  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://askpreston.com/projects/pagecast/index.html">Pagecast
1.1.0</A> - submit lists of URLs to search engine spiders.  (28-Jul-99)

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From fleck@informatik.uni-bonn.de  Sat Jul 31 06:30:06 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Sat, 31 Jul 99 05:30:06 GMT
Subject: [fm] Gnumeric 0.31
Message-ID: <mt2.0-28810-933399006@news.informatik.uni-bonn.de>

  Gnumeric
  Miguel de Icaza - September 30th 1998, 17:52 EST

  Gnumeric is a powerful and easy to use spreadsheet program from the
  GNOME project. The goal for this spreadsheet is to compete with the
  commercial offerings. Users of Excel should be already familiar with
  Gnumeric advanced features. A plugin system lets you extend Gnumeric
  with GPL extensions, and an optional Python and Perl plugins let you
  define complex functions in those popular languages.

             Download: ftp://ftp.gnome.org/pub/GNOME/sources/gnumeric/
     Red Hat packages: ftp://ftp.gnome.org/pub/GNOME/redhat/
          Mirror List: http://www.gnome.org/ftpmirrors.shtml
             Homepage: http://www.gnome.org/gnumeric/

            Changelog: http://www.gnome.org/gnumeric/gnumeric-0.31

          Stable Version: 0.27
              Development
                 Version: 0.31
                  Author: Miguel de Icaza
                 License: GPL
                Category: GNOME/Applications
             Appindex ID: 907192372


  Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.gnome.org/gnumeric/">Gnumeric 0.31</A> - another
snapshot of the GNOME project's spreadsheet application; allows writing
complex functions in Python and Perl.  (30-Jul-99)

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From fleck@informatik.uni-bonn.de  Sat Jul 31 06:34:09 1999
From: fleck@informatik.uni-bonn.de (Markus Fleck)
Date: Sat, 31 Jul 99 05:34:09 GMT
Subject: [fm] The BeOpen.com OO-Browser
Message-ID: <mt2.0-28810-933399249@news.informatik.uni-bonn.de>

  The BeOpen.com OO-Browser
  RSW - July 29th 1999, 23:15 EST

  The BeOpen.com OO-Browser is a multi-windowed, interactive
  object-oriented class browser similar in use to the well-known
  Smalltalk browsers. It is unique in a number of respects foremost of
  which is that it works well with a multiplicity of object-oriented
  languages. It provides both textual views within an editor and
  graphical views under the X window system and Windows. Support for C,
  C++, Common Lisp and its Object System (CLOS), Eiffel, Java,
  Objective-C, Python and Smalltalk class browsing is included.

                Download: http://www.BeOpen.com/products.html
                Homepage: http://www.BeOpen.com/
               Changelog: http://www.BeOpen.com/BR-RELEASE

          Stable Version: 4.06
                  Author: BeOpen.com
                 License: GPL
                Category: Development/Tools
              Depends on: BeOpen.com InfoDock, XEmacs or Emacs
             Appindex ID: 933304552

   Freshmeat (c) 1999 scoop@freshmeat.net

<P><A HREF="http://www.BeOpen.com/">BeOpen.com OO-Browser</A> -
multi-windowed, interactive object-oriented class browser; includes
support for Python class browsing.  (30-Jul-99)

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From tim_one@email.msn.com  Sat Jul 31 06:34:37 1999
From: tim_one@email.msn.com (Tim Peters)
Date: Sat, 31 Jul 99 05:34:37 GMT
Subject: NatLink v001:  Talk to your Python!
Message-ID: <mt2.0-28810-933399277@news.informatik.uni-bonn.de>

Apologies if you've seen this before:  a coworker posted it to the python
and announce groups, but I never saw it come across on their mailing-list
versions.  So I'm mailing it to both.

Original msg, w/ HTML citation appended:


     NatLink v001 by Joel Gould

I would like to announce the availability of a package which allows Python
programs to use large vocabulary speech recognition by interfacing to Dragon
NaturallySpeaking.

NatLink is a Python extension module which allows direct access and control
of Dragon NaturallySpeaking.  Dragon NaturallySpeaking is the best selling
large vocabulary (i.e. dictation) speech recognition program commercially
available.

NatLink requires that you already have a copy of Dragon NaturallySpeaking
(sorry).  It also only runs under Windows 95/98/NT (sorry again).

But with NatLink, you can:

(1) add speech recognition to your Python programs
(2) control Dragon NaturallySpeaking from Python
(3) write voice macros in Python for Dragon NaturallySpeaking

For more details, visit:
http://www.synapseadaptive.com/joel/natlink.htm

Note: NatLink is not a product but a freely downloadable package.

Joel Gould
joelg@alum.mit.edu

<P><A HREF="http://www.synapseadaptive.com/joel/natlink.htm">NatLink
v001</A> - speech recognition via Dragon NaturallySpeaking.  (31-Jul-99)

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