Python-сообщество

Можно так:

>>> class A( object):
def __new__( cls, parent=True ):
klass = object.__new__(cls)
if parent:
klass.a = cls(False)
return klass

def __init__( self, *parent ):
if ‘a’ in dir(self):
print ‘Hallo! I am a parent’
else:
print “Hallo! I am a child”


>>> a = A()
Hallo! I am a child
Hallo! I am a parent