PEP 3139 – Cleaning out sys and the “interpreter” module

PEP: 3139
Title: Cleaning out sys and the “interpreter” module
Author: Benjamin Peterson <benjamin at python.org>
Status: Rejected
Type: Standards Track
Created: 04-Apr-2008
Python-Version: 3.0

Rejection Notice
Abstract
Rationale
Specification
Transition Plan
Open Issues
References
Copyright

Rejection Notice

Guido’s -0.5 put an end to this PEP. See https://mail.python.org/pipermail/python-3000/2008-April/012977.html.

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:

Data and functions that are available in all Python implementations and deal with the general running of a Python virtual machine.
- argv
- byteorder
- path, path_hooks, meta_path, path_importer_cache, and modules
- 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, call_tracing
- getwindowsversion
- maxint and maxunicode
- platform
- ps1 and ps2
- stdin, stderr, stdout, __stdin__, __stderr__, __stdout__
- tracebacklimit
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
- subversion
- builtin_module_names
- callstats
- intern

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 1!

Moving these items off to another module would send a clear message to other Python implementations 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 2; 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 second list of items above will be split into the stdlib as follows:

The interpreter module

get/setrecursionlimit
get/setcheckinterval
_getframe and _current_frame
get/setdlopenflags
settscdumps
api_version
winver
dllhandle
float_info
_clear_type_cache
subversion
builtin_module_names
callstats
intern

The gc module:

getrefcount
_compact_freelists

Transition Plan

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

Open Issues

What should move?

dont_write_bytecode

Some believe that the writing of bytecode is an implementation detail and should be moved 3. The counterargument is that all current, complete Python implementations do write some sort of bytecode, so it is valuable to be able to disable it. Also, if it is moved, some wish to put it in the imp module.