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

Benjamin Peterson musiccomposition at gmail.com
Sat Apr 5 18:13:26 CEST 2008

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.

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


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.


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

1. Data and functions that are available in all Python implementations and
   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
in it [#bug-1522]_!

Other implementations have clearly struggled with what to do about the
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 off to another module would send a clear message about what functions
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


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


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


.. [#bug-1522]


.. [#types-removal]


.. [#pyvm-name]



    This document has been placed in the public domain.

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> -Brett

Benjamin Peterson
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