builtins.rst

:mod:`builtins` --- Built-in objects

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

---

This module provides direct access to all 'built-in' identifiers of Python; for example, builtins.open is the full name for the built-in function :func:`open`. See :ref:`built-in-funcs` and :ref:`built-in-consts` for documentation.

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 builtins

def open(path):
    f = builtins.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__ made available as part of their globals. The value of __builtins__ is normally either this module or the value of this module's :attr:`~object.__dict__` attribute. Since this is an implementation detail, it may not be used by alternate implementations of Python.