Hello,
I would like to create a hierarchy classes, where the leaves have a
special attribute called "producer_id". In addition, I would like to
have a function that can give me back the class assigned to any
producer_id value. I tried to implement this with a metaclass, but I
failed. Please help me, what I did wrong?
Thanks,
Laszlo
class ProducerHandlerType(type):
producer_handlers = {}
@classmethod
def registerProducerHandler(cls,producer_id):
ph = cls.producer_handlers
if ph.has_key(producer_id):
ccls = ph[producer_id]
raise Exception("This producer already has a calculator:
"+str(ccls))
else:
print "Registering "+str(cls)+" for producer_id=",producer_id
ph[producer_id] = cls
def __init__(cls,name,bases,dct):
super(ProducerHandlerType,cls).__init__(cls,name,bases,dct)
if hasattr(cls,'producer_id'):
cls.registerProducerHandler(getattr(cls,'producer_id'))
else:
print "No producer_id for ",str(cls)
class A(ProducerHandlerType):
pass
class B(A):
producer_id = 1
class C(A):
producer_id = 2
# Metaclass methods are not called above, and the line below prints an
empty dict. :-(
print B.producer_handlers
--
http://mail.python.org/mailman/listinfo/python-list
