[stdlib-sig] Proposal: new "interpreter" module

[Benjamin Peterson]

On Sat, Apr 5, 2008 at 10:37 AM, Brett Cannon <brett at python.org> wrote:

> On Sat, Apr 5, 2008 at 4:58 PM, Benjamin Peterson
> <musiccomposition at gmail.com> wrote:
> > Here's an updated version:
> >
> >
> >    - display_hook, stdout, stdin, and stderr
> >    - flags and warn_options
> >    - settrace, and setprofile
> >    - traceback, excepthook
> >    - etc...
> >
>
> You still need to get rid of the "etc.". Beyond being explicit, it
> makes it easier for people reviewing the PEP to see what they think
> might be better placed in the new module.

PEP: XXX
Title: The interpreter module
Version: $Revision$
Last-Modified: $Date$
Author: Benjamin Peterson
Status: Draft
Type: Standards Track
Content-Type: text/x-rst
Created: 4-April-2008
Python-Version: 3.0


Abstract
========

This PEP proposes a new low-level module for CPython-specific interpreter
functions in order to clean out the sys module and separate general Python
functionality from implementation details.


Rationale
=========

The sys module currently contains functions and data that can be put into
two
major groups:

1. Data and functions that are available in all Python implementations and
deal
   with the general running of a Python VM.

   - argv
   - byteorder
   - builtin_module_names, path, and modules
   - subversion, copyright, hexversion, version, and version_info
   - displayhook, __displayhook__
   - excepthook, __excepthook__, exc_info, and exc_clear
   - exec_prefix and prefix
   - executable
   - exit
   - flags, py3kwarning, dont_write_bytecode, and warn_options
   - getfilesystemencoding
   - get/setprofile
   - get/settrace
   - getwindowsversion
   - maxint and maxunicode
   - platform
   - ps1 and ps2
   - stdin, stderr, stdout, __stdin__, __stderr__, __stdout__
   - tracebacklimit


2. Data and functions that affect the CPython interpreter.

   - get/setrecursionlimit
   - get/setcheckinterval
   - _getframe and _current_frame
   - getrefcount
   - get/setdlopenflags
   - settscdumps
   - api_version
   - winver
   - dllhandle
   - float_info
   - _compact_freelists
   - _clear_type_cache

The second collections of items has been steadily increasing over the years
causing clutter in sys.  Guido has even said he doesn't recognize some of
things
in it [#bug-1522]_!

Other implementations have clearly struggled with what to do about the
contents
of sys they can't implement but must to retain compatibility.  For example,
Jython's sys module has dud set/getrecursionlimit functions.  Moving these
items
items off to another module would send a clear message about what functions
need
and need not be implemented.

It has also been proposed that the contents of types module be distributed
across the standard library [#types-removal]_; the interpreter module would
provide an excellent resting place for internal types like frames and code
objects.

Specification
=============

A new builtin module named "interpreter" (see `Naming`_) will be added.  The
functions mentioned in the second list above will be moved to it.


Transition Plan
===============

Once implemented in 3.x, the interpreter module will be back-ported to 2.6.
Py3k warnings will be added the the sys functions it replaces.


Open Issues
===========

Naming
------

The author proposes the name "interpreter" for the new module.  "pyvm" has
also
been suggested [#pyvm-name]_.


References
==========

.. [#bug-1522]

   http://bugs.python.org/issue1522

.. [#types-removal]

   http://mail.python.org/pipermail/stdlib-sig/2008-April/000172.html

.. [#pyvm-name]

   http://mail.python.org/pipermail/python-3000/2007-November/011351.html

Copyright
=========

    This document has been placed in the public domain.



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>
>
> -Brett
>



-- 
Cheers,
Benjamin Peterson
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