def itersubclasses(cls, _seen=None): """ itersubclasses(cls) Generator over all subclasses of a given class, in depth first order. >>> list(itersubclasses(int)) == [bool] True >>> class A(object): pass >>> class B(A): pass >>> class C(A): pass >>> class D(B,C): pass >>> class E(D): pass >>> >>> for cls in itersubclasses(A): ... print(cls.__name__) B D E C >>> # get ALL (new-style) classes currently defined >>> [cls.__name__ for cls in itersubclasses(object)] #doctest: +ELLIPSIS ['type', ...'tuple', ...] """ if not isinstance(cls, type): raise TypeError('itersubclasses must be called with ' 'new-style classes, not %.100r' % cls) if _seen is None: _seen = set() try: subs = cls.__subclasses__() except TypeError: # fails only when cls is type subs = cls.__subclasses__(cls) for sub in subs: if sub not in _seen: _seen.add(sub) yield sub for sub in itersubclasses(sub, _seen): yield sub if __name__ == '__main__': import doctest doctest.testmod(verbose=1)