77 lines
2.2 KiB
Python
77 lines
2.2 KiB
Python
# -*- coding: UTF-8 -*-
|
|
# -*- Mode: Python; py-indent-offset: 4 -*-
|
|
#
|
|
# Copyright (c) 2013 Helmut Merz helmutm@cy55.de
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation; either version 2 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program 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 General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program; if not, write to the Free Software
|
|
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
#
|
|
|
|
"""
|
|
The relation package provides all you need for setting up dyadic and
|
|
triadic relations.
|
|
"""
|
|
|
|
from persistent import Persistent
|
|
from zope.interface import implements
|
|
from interfaces import IPredicate
|
|
from interfaces import IRelation, IDyadicRelation, ITriadicRelation
|
|
from interfaces import IRelatable
|
|
|
|
class Relation(Persistent):
|
|
|
|
implements(IPredicate, IRelation)
|
|
|
|
order = 0
|
|
relevance = 1.0
|
|
fallback = None
|
|
|
|
@classmethod
|
|
def getPredicateName(cls):
|
|
return '%s.%s' % (cls.__module__, cls.__name__)
|
|
|
|
@property
|
|
def ident(self):
|
|
return self.getPredicateName()
|
|
|
|
def validate(self, registry=None):
|
|
return True
|
|
|
|
def checkRelatable(self, *objects):
|
|
for obj in objects:
|
|
if obj is not None and not IRelatable.providedBy(obj):
|
|
raise(ValueError, 'Objects to be used in relations '
|
|
'must provide the IRelatable interface.')
|
|
|
|
|
|
class DyadicRelation(Relation):
|
|
|
|
implements(IDyadicRelation)
|
|
|
|
def __init__(self, first, second):
|
|
self.first = first
|
|
self.second = second
|
|
self.checkRelatable(first, second)
|
|
|
|
|
|
class TriadicRelation(Relation):
|
|
|
|
implements(ITriadicRelation)
|
|
|
|
def __init__(self, first, second, third):
|
|
self.first = first
|
|
self.second = second
|
|
self.third = third
|
|
self.checkRelatable(first, second, third)
|
|
|