python-peps/pep-0294.txt

PEP: 294
Title: Type Names in the types Module
Version: $Revision$
Last-Modified: $Date$
Author: oren at hishome.net (Oren Tirosh)
Status: Rejected
Type: Standards Track
Content-Type: text/x-rst
Created: 19-Jun-2002
Python-Version: 2.5
Post-History:



Abstract
========

This PEP proposes that symbols matching the type name should be added
to the types module for all basic Python types in the types module::

    types.IntegerType -> types.int
    types.FunctionType -> types.function
    types.TracebackType -> types.traceback
     ...

The long capitalized names currently in the types module will be
deprecated.

With this change the types module can serve as a replacement for the
new module.  The new module shall be deprecated and listed in PEP 4.


Pronouncement
=============

A centralized repository of type names was a mistake.  Neither the
"types" nor "new" modules should be carried forward to Python 3.0.

In the meantime, it does not make sense to make the proposed updates
to the modules.  This would cause disruption without any compensating
benefit.

Instead, the problem that some internal types (frames, functions,
etc.) don't live anywhere outside those modules may be addressed by
either adding them to ``__builtin__`` or sys.  This will provide a
smoother transition to Python 3.0.


Rationale
=========

Using two sets of names for the same objects is redundant and
confusing.

In Python versions prior to 2.2 the symbols matching many type names
were taken by the factory functions for those types.  Now all basic
types have been unified with their factory functions and therefore the
type names are available to be consistently used to refer to the type
object.

Most types are accessible as either builtins or in the new module but
some types such as traceback and generator are only accessible through
the types module under names which do not match the type name.  This
PEP provides a uniform way to access all basic types under a single
set of names.


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

The types module shall pass the following test::

    import types
    for t in vars(types).values():
        if type(t) is type:
    assert getattr(types, t.__name__) is t

The types 'class', 'instance method' and 'dict-proxy' have already
been renamed to the valid Python identifiers 'classobj',
'instancemethod' and 'dictproxy', making this possible.


Backward compatibility
======================

Because of their widespread use it is not planned to actually remove
the long names from the types module in some future version.  However,
the long names should be changed in documentation and library sources
to discourage their use in new code.


Reference Implementation
========================

A reference implementation is available in
`issue #569328 <https://bugs.python.org/issue569328>`_.


Copyright
=========

This document has been placed in the public domain.

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