2e4f320fe7
git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@2138 fd906abe-77d9-0310-91a1-e0d9ade77398
74 lines
2.1 KiB
Python
74 lines
2.1 KiB
Python
# -*- coding: UTF-8 -*-
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# -*- Mode: Python; py-indent-offset: 4 -*-
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#
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# Copyright (c) 2005 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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The relation package provides all you need for setting up dyadic and
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triadic relations.
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$Id$
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"""
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from persistent import Persistent
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from zope.interface import implements
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from interfaces import IPredicate
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from interfaces import IRelation, IDyadicRelation, ITriadicRelation
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from interfaces import IRelatable
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class Relation(Persistent):
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implements(IPredicate, IRelation)
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order = 0
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relevance = 1.0
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@classmethod
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def getPredicateName(cls):
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return '%s.%s' % (cls.__module__, cls.__name__)
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def validate(self, registry=None):
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return True
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def checkRelatable(self, *objects):
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for obj in objects:
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if obj is not None and not IRelatable.providedBy(obj):
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raise(ValueError, 'Objects to be used in relations '
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'must provide the IRelatable interface.')
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class DyadicRelation(Relation):
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implements(IDyadicRelation)
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def __init__(self, first, second):
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self.first = first
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self.second = second
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self.checkRelatable(first, second)
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class TriadicRelation(Relation):
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implements(ITriadicRelation)
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def __init__(self, first, second, third):
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self.first = first
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self.second = second
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self.third = third
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self.checkRelatable(first, second, third)
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