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