1
2:mod:`__builtin__` --- Built-in objects
3=======================================
4
5.. module:: __builtin__
6   :synopsis: The module that provides the built-in namespace.
7
8
9This module provides direct access to all 'built-in' identifiers of Python; for
10example, ``__builtin__.open`` is the full name for the built-in function
11:func:`open`.  See :ref:`built-in-funcs` and :ref:`built-in-consts` for
12documentation.
13
14
15This module is not normally accessed explicitly by most applications, but can be
16useful in modules that provide objects with the same name as a built-in value,
17but in which the built-in of that name is also needed.  For example, in a module
18that wants to implement an :func:`open` function that wraps the built-in
19:func:`open`, this module can be used directly::
20
21   import __builtin__
22
23   def open(path):
24       f = __builtin__.open(path, 'r')
25       return UpperCaser(f)
26
27   class UpperCaser:
28       '''Wrapper around a file that converts output to upper-case.'''
29
30       def __init__(self, f):
31           self._f = f
32
33       def read(self, count=-1):
34           return self._f.read(count).upper()
35
36       # ...
37
38.. impl-detail::
39
40   Most modules have the name ``__builtins__`` (note the ``'s'``) made available
41   as part of their globals.  The value of ``__builtins__`` is normally either
42   this module or the value of this modules's :attr:`~object.__dict__` attribute.  Since
43   this is an implementation detail, it may not be used by alternate
44   implementations of Python.
45