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.

Copyright

This document has been placed in the public domain.