53ae9f332a
git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@1602 fd906abe-77d9-0310-91a1-e0d9ade77398
116 lines
3.1 KiB
Python
116 lines
3.1 KiB
Python
#
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# Copyright (c) 2007 Helmut Merz helmutm@cy55.de
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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"""
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Advanced properties, i.e. the lazy one and Philipp von Weitershausen's
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read & write properties.
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Based on zope.cachedescriptors.property.Lazy and including code from
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http://cheeseshop.python.org/pypi/rwproperty.
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$Id$
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"""
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class lzprop(object):
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"""Declare lazy properties that are calculated only if needed,
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and just once.
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See property.txt for example usage.
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"""
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def __init__(self, func):
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self.func = func
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def __get__(self, inst, class_):
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if inst is None: return self
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value = self.func(inst)
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inst.__dict__[self.func.__name__] = value
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return value
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# Read & write properties
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#
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# Copyright (c) 2006 by Philipp "philiKON" von Weitershausen
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# philikon@philikon.de
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#
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# Freely distributable under the terms of the Zope Public License, v2.1.
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#
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# See rwproperty.txt for detailed explanations
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#
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import sys
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__all__ = ['getproperty', 'setproperty', 'delproperty']
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class rwproperty(object):
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def __new__(cls, func):
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name = func.__name__
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# ugly, but common hack
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frame = sys._getframe(1)
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locals = frame.f_locals
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if name not in locals:
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return cls.createProperty(func)
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oldprop = locals[name]
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if isinstance(oldprop, property):
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return cls.enhanceProperty(oldprop, func)
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raise TypeError("read & write properties cannot be mixed with "
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"other attributes except regular property objects.")
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# this might not be particularly elegant, but it's easy on the eyes
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@staticmethod
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def createProperty(func):
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raise NotImplementedError
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@staticmethod
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def enhanceProperty(oldprop, func):
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raise NotImplementedError
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class getproperty(rwproperty):
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@staticmethod
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def createProperty(func):
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return property(func)
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@staticmethod
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def enhanceProperty(oldprop, func):
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return property(func, oldprop.fset, oldprop.fdel)
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class setproperty(rwproperty):
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@staticmethod
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def createProperty(func):
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return property(None, func)
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@staticmethod
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def enhanceProperty(oldprop, func):
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return property(oldprop.fget, func, oldprop.fdel)
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class delproperty(rwproperty):
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@staticmethod
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def createProperty(func):
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return property(None, None, func)
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@staticmethod
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def enhanceProperty(oldprop, func):
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return property(oldprop.fget, oldprop.fset, func)
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