Consider the following module:
================================
class NewDict(dict):
parent = None
def __setitem__(self, key, value):
print "My parent is", self.parent
super(NewDict, self).__setitem__(key, value)
class Zero(object):
children = NewDict()
def __init__(self):
self.children.parent = self
class One(Zero):
pass
class Two(One):
pass
a = One()
a.children["spam"] = "baked beans"
b = Two()
b.children["eggs"] = "bacon"
================================
When the above module is executed, the output looks something like this:
My parent is <__main__.One object at 0x00BA27B0>
My parent is <__main__.Two object at 0x00B9D170>
...which is great, just what I wanted. Each dictionary instance reports
correctly which object instance is its container.
However, I would like to find some automagic way of having NewDict
figure out what object instance it is on without resorting to having the
container class instance poke a reference to itself into the NewDict
instance (i.e. the line in Zero.__init__()).
I have tried using inspect.getmembers() and walking up the
sys._getframe() stack, but to no avail. Am I missing something here?
Or is it simply not possible for the NewDict instance to figure out for
itself what its container is?
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