Question

Is a reference exists from an attribute to the attribute holder?
Here is an example what I mean:

class classA(object):
    def __init__(self):
        pass

class classB(object):
    def __init__(self):
        self.a=classA()

    def methodB(self):
        print "ClassB-s methodB called"

b=classB()
a=b.a

Is it possible to reference b from a? I like to call methodB from a.

Answer 1

No, not really.

When you initialize b.a, it becomes a reference to a classA object:

>>> b.a
<__main__.classA object at 0x7feeb904df10>

To call the method, you could pass the parent object to classA:

>>> class classA(object):
...    def __init__(self, parent):
...        self.parent = parent
...    
...    def method(self):
...        self.parent.methodB()
...
>>>
>>> class classB(object):
...    def __init__(self):
...        self.a=classA(self)
...
...    def methodB(self):
...        print "ClassB-s methodB called"
...
>>> b = classB()
>>> a = b.a
>>> a.method()
ClassB-s methodB called

From there, you have access to the whole parent.