Thanks everyone, moving the declaration to the class's __init__ method
did the trick. Now there's just one little problem left. I'm trying to
create a list that holds the parents for each instance in the
hierarchy. This is what my code looks like now:
-----------------------------------------
class A:
def __init__(self, parents=None):
self.sub = dict()
if parents:
self.parents = parents
else:
self.parents = []
def sub_add(self, cls):
hierarchy = self.parents
hierarchy.append(self)
obj = cls(hierarchy)
self.sub[obj.id] = obj
class B(A):
id = 'inst'
base = A()
base.sub_add(B)
base.sub['inst'].sub_add(B)
print
print vars(base)
print
print vars(base.sub['inst'])
print
print vars(base.sub['inst'].sub['inst'])
---------------------------------------------
The output from this program is the following:
{'parents': [<__main__.A instance at 0x02179468>, <__main__.B instance
at 0x021794B8>], 'sub': {'inst': <__main__.B instance at 0x021794B8>}}
{'parents': [<__main__.A instance at 0x02179468>, <__main__.B instance
at 0x021794B8>], 'sub': {'inst': <__main__.B instance at 0x021794E0>}}
{'parents': [<__main__.A instance at 0x02179468>, <__main__.B instance
at 0x021794B8>], 'sub': {}}
As you can see, the problem looks similar to the one before: All the
instances have an identical parent list. However, I don't understand
why as self.parents is declared in the __init__ method. Any ideas?
What I want is for the first instance to have an empty list, the
second to have one element in the list and the third to have two
parent elements.
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