1 

     2 :mod:`__builtin__` --- Built-in objects

     3 =======================================

     4 

     5 .. module:: __builtin__

     6    :synopsis: The module that provides the built-in namespace.

     7 

     8 

     9 This module provides direct access to all 'built-in' identifiers of Python; for

    10 example, ``__builtin__.open`` is the full name for the built-in function

    11 :func:`open`.  See chapter :ref:`builtin`.

    12 

    13 This module is not normally accessed explicitly by most applications, but can be

    14 useful in modules that provide objects with the same name as a built-in value,

    15 but in which the built-in of that name is also needed.  For example, in a module

    16 that wants to implement an :func:`open` function that wraps the built-in

    17 :func:`open`, this module can be used directly::

    18 

    19    import __builtin__

    20 

    21    def open(path):

    22        f = __builtin__.open(path, 'r')

    23        return UpperCaser(f)

    24 

    25    class UpperCaser:

    26        '''Wrapper around a file that converts output to upper-case.'''

    27 

    28        def __init__(self, f):

    29            self._f = f

    30 

    31        def read(self, count=-1):

    32            return self._f.read(count).upper()

    33 

    34        # ...

    35 

    36 As an implementation detail, most modules have the name ``__builtins__`` (note

    37 the ``'s'``) made available as part of their globals.  The value of

    38 ``__builtins__`` is normally either this module or the value of this modules's

    39 :attr:`__dict__` attribute.  Since this is an implementation detail, it may not

    40 be used by alternate implementations of Python.

    41