Python Knowledge Base Update -- March 3rd, 2000
Gregoire Welraeds
greg at perceval.be
Sat Mar 4 16:57:04 EST 2000
In reply to the message of Nathan Wallace sent on Mar 4 (see below) :
This is a really good job!!
--
Life is not fair
But the root password helps
--
Gregoire Welraeds
greg at perceval.be
Perceval Development team
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On Sat, 4 Mar 2000, Nathan Wallace wrote:
> Date: Sat, 04 Mar 2000 04:29:38 GMT
> From: Nathan Wallace <nathan at synop.com>
> To: python-list at python.org
> Newsgroups: comp.lang.python
> Subject: Python Knowledge Base Update -- March 3rd, 2000
>
> Thanks to everyone who is contributing. Remember, every contribution
> increases your chances of winning the Palm V. Any contribution, even
> spelling fixes or rearranging entries helps improve the Knowledge Base:
>
> http://python.faqts.com
>
> Cheers,
>
> Nathan
>
>
> ## Unanswered Questions ########################################
>
>
> -------------------------------------------------------------
> How do I upload a binary file using ftplib?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1457
> -------------------------------------------------------------
> Mike Hostetler
>
>
>
> ## New Entries #################################################
>
>
> -------------------------------------------------------------
> How can I use a line printer from Python on different systems?
> Is there system independent access to a line printer from Python?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1504
> -------------------------------------------------------------
> Nathan Wallace
> Randall Hopper
>
> Well, when you say system-independent, that makes it more of a
> challenge:
>
> MSWin: Maybe MSWin provides an abstract API to print to a printer.
> But what if there are multiple printers? MSWin progs usually have
> a Printer Setup... so the user can set this, among other things
> (page parms, orientation, etc.)
>
> UNIX: Is this system using lp? Or lpr? Or ... Assuming we knew,
> then the question is which printer (printer queue) does the user
> want to use? We might assume the user has already set $PRINTER or
> $LPDEST as a preference, but maybe that printer only groks
> Postscript and we want to print plain text. Or vice versa.
>
> DOS: How do you know which parallel port has a printer on it, if any?
> Maybe none do? Maybe multiple? You could just exec PRINT and take
> your chances, but... And you don't know what preamble control
> strings might be required. For example, some printers are set to
> expect UNIX EOL convention, and some aren't.
>
> For now, it might be best to take your queues off cross-platform apps
> like Netscape and let the user configure the command used to print. The
> print-to-file option is nice too and useful on occasion.
>
>
> -------------------------------------------------------------
> How can I extract all the keys in a formatting string to a list?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1505
> -------------------------------------------------------------
> Nathan Wallace
> Michael Ströder, Johannes Stezenbach
>
> For example, go from:
>
> '%(language)s has %(count)03d quote types.' % vars()
>
> to get:
>
> ['language','count']
>
> Try something like this:
>
> ------------
> class GrabKeys:
> def __init__(self):
> self.keys = []
> def __getitem__(self, name):
> self.keys.append(name)
> return 0 # 0 is apparently compatible with all % format
> characters
>
> gk = GrabKeys()
>
> '%(language)s has %(count)03d quote types.' % gk
>
> print gk.keys
> ------------
>
>
> -------------------------------------------------------------
> What files do I need on my web server to use Python for CGI?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1506
> -------------------------------------------------------------
> Nathan Wallace
> Harry George, Kalle Svensson
>
> Your cgi script is a normal python script -- which means it needs the
> normal python infrastructure (e.g., the interpreter and the std
> libraries). If your homepage is on an ISP which does not support
> python, that could be trouble. You could ask the ISP to install
> python, so you can use it.
>
> You will at least need the main script file plus any modules it uses
> that are not in the standard library. On some webhosts, you will also
> have to rename the main script file with a .cgi extension. If the
> script uses any data files, you will have to upload them too.
>
> Also remember, if you usually do
>
> #!/usr/bin/env python
>
> You may have to do:
>
> #!/usr/bin/python (or whatever the actual absolute path may be)
>
> (It is probably a poor idea to try to pick just a few of the std
> libraries to upload, since you need the interpreter anyway.)
>
>
> -------------------------------------------------------------
> Are there any bug tracking systems written in Python?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1508
> -------------------------------------------------------------
> Nathan Wallace
> Alessandro Bottoni
>
> There is a nice project-management, task-tracking (problem-tracking)
> system based on ZOPE (and hence on Python) out there:
>
> http://bits.netizen.com.au/Xen/
>
> XEN seems to be a quite interesting tool, really...
>
> I do hope they will get some sponsorship from software carpentry, CNRI
> or GNU.
>
> You might also like to check out:
>
> http://software-carpentry.codesourcery.com/
>
>
> -------------------------------------------------------------
> How can I check that the Python version is recent enough to run my
> program?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1509
> -------------------------------------------------------------
> Nathan Wallace
> Fredrik Lundh, Oleg Broytmann
>
> Note that [1, 5, 2] < [1, 6]. in other words, this will do what you
> want:
>
> import string, sys
> version = string.split(string.split(sys.version)[0], ".")
> if map(int, version) < [1, 5, 2]:
> print "sorry"
>
> I can be better to not check the version - this will bound poor user to
> one version. Instead, check for the feature you need. You need a
> library? Try to import it and fall back gracefully:
>
> try:
> import pagecast_lib
> except ImportError:
> print_error()
>
> if not pagecast_lib.has_key("I_need_IT"):
> print_another_error()
>
>
> -------------------------------------------------------------
> Can I use Python scripting inside a C app?
> How can I use Python as an internal scripting language?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1512
> -------------------------------------------------------------
> Nathan Wallace
> Jon K Hellan
>
> Download the Python documentation at "http://www.python.org/doc/". You
> want "Extending and Embedding" for overview, and "Python/C API" for
> more detail. You can also check out the tutorial at
> "http://starship.python.net/crew/arcege/extwriting/pyext.html".
>
> There's also a chapter in Mark Lutz' "Programming Python" from
> O'Reilly.
>
>
> -------------------------------------------------------------
> How do you redirect stdout to your own place, such as a Win32 anonymous
> pipe, before you even call Py_Initialize?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1510
> -------------------------------------------------------------
> Nathan Wallace
> Niels Diepeveen
>
> Something like this will probably work:
>
> int stdoutfds[2];
> if (_pipe(stdoutfds, 512, _O_BINARY))
> ....
> if (_dup2(stdoutfds[1], 1) /* Redirect stdout */
> ....
> if (_dup2(stdoutfds[1], 2) /* Redirect stderr */
> ....
> _close(stdoutfds[1]);
>
>
> -------------------------------------------------------------
> Is it possible to not have to explicitly do imports?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1514
> -------------------------------------------------------------
> Nathan Wallace
> Paul Prescod
>
> I would suggest instead that you add an object to the globals dictionary
> in your site setup. It could be called "mods" (for brevity). You would
> hook up "mods.__getattr__" so that you would say:
>
> fl=mods.glob.glob('*')
>
> You would use __import__ in mods.__getattr__
>
> I thought about this once and it seemed pretty cool to me as a shortcut.
> You could argue that we could dump the import statement...(but I
> wouldn't)
>
> Having an explicit object as the root for the dynamically generated
> package tree would be more Pythonic than having every module magically
> appear in your global package namespace.
>
> Package support needs more thinking through...
>
>
> -------------------------------------------------------------
> How do I format my request to get an url/socket when there is a proxy in
> themiddle?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1515
> -------------------------------------------------------------
> Nathan Wallace
> David Fisher
>
> urllib has proxy support built-in, but not documented.
>
> >>> import urllib
> >>> proxy = { 'http': r'http://192.168.1.1:3128'} #squid proxy on my
> local network
> >>> u = urllib.URLopener(proxies = proxy)
> >>> f = u.open(r'http://www.python.org')
> >>> print f.read()
> <HTML>
> <!-- THIS PAGE IS AUTOMATICALLY GENERATED. DO NOT EDIT. -->
> <!-- Mon Feb 28 11:00:24 2000 -->
> <!-- USING HT2HTML 1.1 -->
> <!-- SEE http://www.python.org/~bwarsaw/software/pyware.html -->
> <!-- User-specified headers:
> Title: Python Language Website
>
> etc, etc, etc
>
> you can add other proxies for ftp, et al. , i haven't done it, but I'm
> known for my blind faith
>
>
> -------------------------------------------------------------
> How can I run another application (non Python) from within a Python
> script and
> capture its output?
> Does os.popen() work from pythonw?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1516
> -------------------------------------------------------------
> Nathan Wallace
> Jesper Hertel, Niels Diepeveen
>
> os.popen(command_line) returns a pipe from wich you can read the
> standard output from the command given by command_line.
>
> That is, for example,
>
> a = os.popen("dir").read()
>
> runs the command "dir" and puts the entire output from the command in
> the variable a.
>
> Another function os.popen2() also returns standard error output from the
> command, but this does not work in Windows, unfortunately.
>
> Be careful, os.popen only works in a console session, not from pythonw.
> This is a problem in the C library.
>
>
> ## Edited Entries ##############################################
>
>
> -------------------------------------------------------------
> How can I read and interpret email attachments using Python?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1324
> -------------------------------------------------------------
> Sean Blakey, Shae Erisson, Nathan Wallace
> Oleg Broytmann,http://starship.python.net/~arcege/modules/index.html
>
> Goto
>
> http://sun.med.ru/~phd/Software/Python/misc.html
>
> and download
>
> extract_mime.tgz
>
> There you'll find an example and some docs. Just feed a MIME message
> into the program...
>
> Assuming you have a file pointer to the message, you can create a
> mimetools.Message object to access a multipart mime message. Here is a
> snippet of code:
>
> def decode_item(item):
> '''
> Decode an indevidual mime item
>
> item should be a mimetools.Message object.
> '''
> encoding = item.getencoding()
> name = item.getparam('name')
> print 'Decoding to', name
> outfile = open(name, 'wb') # Write the decoded
> # Attatchment to a file
> mimetools.decode(item.fp, outfile, encoding)
>
> def decode_multipart(datafile):
> '''
> Decode a multipart MIME message.
>
> datafile is the filepointer to a MIME mesage.
> '''
> msg = mimetools.Message(datafile)
> boundary = msg.getparam('boundary') # The boundry between
> # Message parts
> encoding = msg.getencoding()
> if encoding != '7bit':
> raise 'Unknown encoding!', encoding
> if msg.gettype() != 'multipart/mixed':
> raise 'Message is not multipart!' # This could probably be
> # made more robust
> mmsg = multifile.MultiFile(msg.fp) # Abstract the message as
> # A multifile object
> mmsg.push(boundary)
> while 1:
> mmsg.next()
> if mmsg.last:
> break
> mime_item = mimetools.Message(mmsg)
> decode_item(mime_item)
>
>
> also check out http://starship.python.net/~arcege/modules/index.html
> Mimecntl is a nice way to build and read MIME docs.
>
>
> -------------------------------------------------------------
> How can I trap a keyboard interrupt using Python?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1424
> -------------------------------------------------------------
> Nathan Wallace
> Oleg Orlov
>
> import sys
>
> def Worker(argv):
> while 1:
> pass
>
> try:
> if __name__ =='__main__':
> Worker(sys.argv)
> except KeyboardInterrupt:
> print "Saving state..."
>
>
> -------------------------------------------------------------
> What is the best and fastest way to scan a whole list of foldersto see
> if something has been added or not?
> http://www.faqts.com/knowledge-base/view.phtml/aid/1326
> -------------------------------------------------------------
> Nathan Wallace
> Darrell
>
> If your talking about NT then give this a try.
>
> http://www.dorb.com/darrell/win32WorkSvr/makeThumbsDG.py
>
> def main():
> """
> Use events to avoid polling.
> A sleep is used to give most files a chance to finish
> being writen. Sort of a hack and might not be needed.
> The notification event LAST_WRITE seems to trigger
> at the start and end of writing. So a single file
> will trigger this twice.
> """
> hnd=win32file.FindFirstChangeNotification\
> (os.path.abspath('.')+os.sep+'incoming'\
> ,0, winnt.FILE_NOTIFY_CHANGE_LAST_WRITE )
>
> while 1:
> int = win32event.WaitForSingleObject( hnd, -1)
> # Try to give the file time to finish writing
> time.sleep(2)
> print 'run'
> try:
> passed, failed, skipped = makeThumbNails()
> except:
> if '-d' in sys.argv:
> traceback.print_exc()
> raise ThumbNailException
> win32file.FindNextChangeNotification(hnd)
> --
> http://www.python.org/mailman/listinfo/python-list
>
>
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