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Subject: Re: finding abc's
From: lars van gemerden <lars@rational-it.com>
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Xref: csiph.com comp.lang.python:37706

for future reference, i decided to go with 2 functions:

def common_bases(classes):
    if not len(classes):
        return None
    common =3D set(classes.pop().mro())
    for cls in classes:
        common.intersection_update(cls.mro()) #all subclasses in common    =
  =20
    return [cls for cls in common if not any(sub in common for sub in cls._=
_subclasses__())] #the classes of which no subclasses are present

def unique_common_base(classes):
    while len(classes) > 1:
        classes =3D common_bases(classes)
    return classes.pop()

if i tested and understood correctly, they only take classes in the mro() i=
nto account (which might include abc's), the first gives all common base cl=
asses, the second recursively reduces further to one single class (the latt=
er might not make to much sense, but in my program it is a safe bet for rar=
e cases).

Thanks again for the help,

Cheers, Lars