Question

What I am asking may look weird, but here is an example:

I have a class ‘A’

class A:
    a=1

other I have class ‘B’

class B:
    def __init__(self, obj):
        self.obj = obj # obj is any object

Now I use:

first = A()
second = B(first)
isinstance(second, A)

I want step 3 to be true. i.e. whatever object class B is taking, it should add instance of that object type to object.

Is something like this possible in Python?

Answer 1

You can of course override the __new__ and derive your object from type instead of object effectively creating a class factory…

What you end up doing is very similar to:

b = type('B', (A,), {'obj': A()})

Which generates a class B derived from A, containing that instance of A() – since this is a function you can pass whatever you fancy in for whatever reason you wish to do so.