def _decorator(cls):
missing = object()
for interface in interfaces:
classImplements(cls, interface)
for name in interface:
if getattr(cls, name, missing) is missing:
setattr(cls, name, Passthrough(name, context))
return cls
def _delegates_advice(cls):
"""Add a Passthrough class for each missing interface attribute.
This function connects the decorator class to the delegate class.
Only new-style classes are supported.
"""
interface_spec, contextvar = cls.__dict__['__delegates_advice_data__']
del cls.__delegates_advice_data__
if isinstance(cls, ClassType):
raise TypeError('Cannot use delegates() on a classic class: %s.' % cls)
if IInterface.providedBy(interface_spec):
interfaces = [interface_spec]
else:
interfaces = interface_spec
not_found = object()
for interface in interfaces:
classImplements(cls, interface)
for name in interface:
if getattr(cls, name, not_found) is not_found:
setattr(cls, name, Passthrough(name, contextvar))
return cls
