872fccc529
git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@2465 fd906abe-77d9-0310-91a1-e0d9ade77398
84 lines
2.6 KiB
Python
84 lines
2.6 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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A simple adapter framework.
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$Id$
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"""
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class AdapterFactory(object):
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def __init__(self):
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self._registry = {}
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def register(self, adapter, adapted, name=''):
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""" Register `adapter` class for objects of class `adapted`.
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Optionally associate the adapter with a `name`; thus there
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can be more than one adapter for one class.
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"""
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self._registry[(adapted, name)] = adapter
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def queryAdapter(self, obj, name):
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class_ = type(obj) is type and obj or obj.__class__
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adapter = None
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while adapter is None and class_:
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adapter = self._registry.get((class_, name))
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if adapter is None:
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bases = class_.__bases__
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class_ = bases and bases[0] or None
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return adapter
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def __call__(self, obj, name=''):
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""" Return an adapter instance on `obj` with the `name` given.
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if obj is a class use this class for the adapter lookup, else
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use obj's class.
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If there isn't an adapter directly for the class
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check also for its base classes.
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"""
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adapter = self.queryAdapter(obj, name)
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if adapter is None:
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return None
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return adapter(obj)
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# self-registering adapters
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adapters = AdapterFactory()
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class AdapterType(type):
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""" To be used as metaclass for self-registering adapters.
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"""
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def __init__(cls, name, bases, cdict):
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super(AdapterType, cls).__init__(name, bases, cdict)
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info = list(cdict.get('__adapterinfo__', (adapters, object, '')))
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if len(info) < 2:
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info.append(object)
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if len(info) < 3:
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info.append('')
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factory, adapted, name = info
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factory.register(cls, adapted, name)
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class AdapterBase:
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__metaclass__ = AdapterType
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