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cpython/Doc/library/__builtin__.rst
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:mod:`__builtin__` --- Built-in objects
=======================================
.. module:: __builtin__
:synopsis: The module that provides the built-in namespace.
This module provides direct access to all 'built-in' identifiers of Python; for
example, ``__builtin__.open`` is the full name for the built-in function
:func:`open`. See chapter :ref:`builtin`.
This module is not normally accessed explicitly by most applications, but can be
useful in modules that provide objects with the same name as a built-in value,
but in which the built-in of that name is also needed. For example, in a module
that wants to implement an :func:`open` function that wraps the built-in
:func:`open`, this module can be used directly::
import __builtin__
def open(path):
f = __builtin__.open(path, 'r')
return UpperCaser(f)
class UpperCaser:
'''Wrapper around a file that converts output to upper-case.'''
def __init__(self, f):
self._f = f
def read(self, count=-1):
return self._f.read(count).upper()
# ...
As an implementation detail, most modules have the name ``__builtins__`` (note
the ``'s'``) made available as part of their globals. The value of
``__builtins__`` is normally either this module or the value of this modules's
:attr:`__dict__` attribute. Since this is an implementation detail, it may not
be used by alternate implementations of Python.