Adding a Method to an Existing Object Instance

Question

I\'ve read that it is possible to add a method to an existing object (i.e., not in the class definition) in Python.

I understand that it\'s not always good to do so

Answer 1

I find it strange that nobody mentioned that all of the methods listed above creates a cycle reference between the added method and the instance, causing the object to be persistent till garbage collection. There was an old trick adding a descriptor by extending the class of the object:

def addmethod(obj, name, func):
    klass = obj.__class__
    subclass = type(klass.__name__, (klass,), {})
    setattr(subclass, name, func)
    obj.__class__ = subclass