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##############################################################################
#
# Copyright (c) 2003 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Decorator support
Decorators are proxies that are mostly transparent but that may provide
additional features.
"""
__docformat__ = "reStructuredText"
from zope.interface import providedBy
from zope.interface.declarations import ObjectSpecification
from zope.interface.declarations import ObjectSpecificationDescriptor
from zope.interface.declarations import getObjectSpecification
from zope.proxy import ProxyBase
from zope.proxy import getProxiedObject
class DecoratorSpecificationDescriptor(ObjectSpecificationDescriptor):
"""Support for interface declarations on decorators
"""
def __get__(self, inst, cls=None):
if inst is None:
return getObjectSpecification(cls)
else:
provided = providedBy(getProxiedObject(inst))
# Use type rather than __class__ because inst is a proxy and
# will return the proxied object's class.
cls = type(inst)
return ObjectSpecification(provided, cls)
def __set__(self, inst, value):
raise TypeError("Can't set __providedBy__ on a decorated object")
class SpecificationDecoratorBase(ProxyBase):
"""Base class for a proxy that provides additional interfaces."""
__providedBy__ = DecoratorSpecificationDescriptor()
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