def initialize_internal_attributes (C):
"Prepare a class for life as a child of InternalAttributesClass."
if C.__dict__.has_key('_internal'): return
if not issubclass(C, InternalAttributesClass):
raise ValueError, 'Must be subclass of InternalAttributesClass'
PropertiedClasses.initialize_property_class (C)
C._internal = []
for CP in C.__bases__:
if issubclass(CP, InternalAttributesClass):
initialize_internal_attributes(CP)
for name in CP._internal:
C._internal.append(name)
