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# -*- coding: utf-8 -*-
#
# Copyright (c) 2010 Red Hat, Inc
#
# This file is part of kitchen
#
# kitchen is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# kitchen is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
# more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with kitchen; if not, see <http://www.gnu.org/licenses/>
#
# Authors:
# Toshio Kuratomi <toshio@fedoraproject.org>
'''
In python-2.4, a builtin :class:`set` type was added to python. This module
provides a function to emulate that on python-2.3 by using the :mod:`sets`
module.
:func:`set`
Create a set. If running on python 2.4+ this is the :class:`set`
constructor. If using python-2.3, it's :class:`sets.Set`.
:func:`frozenset`
Create a frozenset. If running on python2.4+ this is the
:class:`frozenset` constructor. If using python-2.3, it's
:class:`sets.ImmutableSet`.
.. versionchanged:: 0.2.0 API: kitchen.pycompat24 1.0.0
Added set and frozenset
'''
import __builtin__
# Setup set and frozenset on this module
# :W0622,C0103: The purpose of this module is to define set and frozenset if
# they aren't in builtins already so we disregard these pylint warnings
#pylint:disable-msg=W0622,C0103
if not hasattr(__builtin__, 'set'):
import sets
set = sets.Set
else:
set = set
if not hasattr(__builtin__, 'frozenset'):
import sets
frozenset = sets.ImmutableSet
else:
frozenset = frozenset
#pylint:enable-msg=W0622,C0103
def add_builtin_set():
'''If there's no set builtin, us the :mod:`sets` module to make one
This function makes sure that a :class:`set` and :class:`frozenset` type
are available in the :mod:`__builtin__` namespace. Since the function
checks whether :class:`set` and :class:`frozenset` are already present in
the :mod:`__builtin__` namespace and refuses to overwrite those if found,
it's safe to call this in multiple places and in scripts run under
python-2.4+, where a more efficient set implementation is already present
in the :mod:`__builtin__` namespace.
However, since this function modifies :mod:`__builtin__` there's no need
to call it more than once so you likely want to do something like this
when your program loads::
myprogram/__init__.py:
from kitchen.pycompat24 import sets
builtinset.add_builtin_set()
You can then use :func:`set` and :func:`frozenset` anywhere in your code::
myprogram/compute.py:
def math_students(algebra_student_list, geometry_student_list):
return set(algebra_student_list) union set(geometry_student_list)
'''
if not hasattr(__builtin__, 'set'):
__builtin__.set = set
if not hasattr(__builtin__, 'frozenset'):
__builtin__.frozenset = frozenset
__all__ = ('add_builtin_set', 'set', 'frozenset')
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