Change python mro at runtime

Question

I\'ve found myself in an unusual situation where I need to change the MRO of a class at runtime.

The code:

class A(object):
    def __init__(self):
          


        

Answer 1

I've found a way to change object's class or rewrite it's mro.

The easiest way is to build a new class with type function:

def upgrade_class(obj, old_class, new_class):
    if obj.__class__ is old_class:
        obj.__class__ = new_class
    else:
        mro = obj.__class__.mro()

        def replace(cls):
            if cls is old_class:
                return new_class
            else:
                return cls

        bases = tuple(map(replace, mro[1:]))
        old_base_class = obj.__class__
        new_class = type(old_base_class.__name__, bases, dict(old_base_class.__dict__))
        obj.__class__ = new_class