source: python/vendor/Python-2.7.6/Doc/library/constants.rst

Last change on this file was 388, checked in by dmik, 11 years ago

python: Update vendor to 2.7.6.
  • Property svn:eol-style set to native
File size: 2.2 KB

Built-in Constants

A small number of constants live in the built-in namespace. They are:

?
.. data:: False

   The false value of the :class:`bool` type.

   .. versionadded:: 2.3
?
.. data:: True

   The true value of the :class:`bool` type.

   .. versionadded:: 2.3
?
.. data:: None

   The sole value of :attr:`types.NoneType`.  ``None`` is frequently used to
   represent the absence of a value, as when default arguments are not passed to a
   function.

   .. versionchanged:: 2.4
      Assignments to ``None`` are illegal and raise a :exc:`SyntaxError`.
?
.. data:: NotImplemented

   Special value which can be returned by the "rich comparison" special methods
   (:meth:`__eq__`, :meth:`__lt__`, and friends), to indicate that the comparison
   is not implemented with respect to the other type.
?
.. data:: Ellipsis

   Special value used in conjunction with extended slicing syntax.
?
.. data:: __debug__

   This constant is true if Python was not started with an :option:`-O` option.
   See also the :keyword:`assert` statement.

Note

The names :data:`None` and :data:`__debug__` cannot be reassigned (assignments to them, even as an attribute name, raise :exc:`SyntaxError`), so they can be considered "true" constants.

????
.. versionchanged:: 2.7
   Assignments to ``__debug__`` as an attribute became illegal.

Constants added by the :mod:`site` module

?

The :mod:`site` module (which is imported automatically during startup, except if the :option:`-S` command-line option is given) adds several constants to the built-in namespace. They are useful for the interactive interpreter shell and should not be used in programs.

???
.. data:: quit([code=None])
          exit([code=None])

   Objects that when printed, print a message like "Use quit() or Ctrl-D
   (i.e. EOF) to exit", and when called, raise :exc:`SystemExit` with the
   specified exit code.
?
.. data:: copyright
          license
          credits

   Objects that when printed, print a message like "Type license() to see the
   full license text", and when called, display the corresponding text in a
   pager-like fashion (one screen at a time).
Note: See TracBrowser for help on using the repository browser.