Safe to change base class in python?

Question

Questions like this exist, but none exactly like this, and I found no completely satisfactory answers.

I'm doing an agent-based biological model. Suppose I have a class of cell type A, and one of type B. They age according to a clock. Suppose when a cell of type A reaches a certain age, it changes to a cell of type B.

I have an inventory of cells. I don't want to just create new B cells, and add them to the inventory, and leave the A cells still in the inventory.

This appears to work, but is it safe?

class B(object):
    pass

class A(object):
    def changeToB(self):
        self.__class__ = B

Or, is there a better approach?

Answer 1

While it may be safe for the interpreter, it is definitely unsafe to one trying to understand what's happening.

It is hard to find a more natural mapping to object design than a biological cell and you are trying to discard what is naturally there. A cell has-a age and various mechanisms turn on and off as a function of age. In the world, an osteoblast doesn't pop out of existence and an osteocyte takes its place, but rather the cell retains its "identity" but behaves differently depending on state values like age.

I'd certainly take considerations like that into the object model if I were coding such a model.

Answer 2

I tried that many years ago while working on a parser. It seemed to do what I wanted at the time, so was safe enough from the language perspective, but now I am older and wiser I don't think I'd use it for code that anyone else might have to maintain - I don't think it's very "safe" from that perspective