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
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 accssible
    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 SourceForge patch
    #569328: http://www.python.org/sf/569328
  

Copyright

    This document has been placed in the public domain.



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