Metaclasses are not called in subclasses. What did I wrong?

Létező letezo at fw.hu
Sun Oct 29 01:47:39 CEST 2006


I use Python 2.4.4. Please read the code below:

-----------------------------------------------------------
from new import classobj

def mymeta(name,bases,clsdict):
    print 'meta: %s'%name
    return classobj(name,bases,clsdict)

class A(object):
    __metaclass__=mymeta

class B(A):
    pass

-----------------------------------------------------------

This should print

meta: A
meta: B

when classes A and B are created. But only meta: B is missing,
since mymeta() is not called when class B is created.

Related python documentation states that mymeta() must be called when B is
created, since metaclasses are looked up in bases classes if not found in
the dictionary of the class itself.

>From Python 2.4.4's manual: "Otherwise, if there is at least one base class,
its metaclass is used (this looks for a __class__ attribute first and if not
found, uses its type)."

Thanks for your help.

Viktor 




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