Function for augmenting object to print stack trace whenever watched attributes are accessed, changed or removed.

spy.py

def patch(obj, attrs):
    import traceback
    class o(object): pass
    class Spy(o):
        def __getattribute__(self, a):
            if a in attrs:
                traceback.print_stack()
            return object.__getattribute__(obj, a)

        def __setattr__(self, a, value):
            if a in attrs:
                traceback.print_stack()
            object.__setattr__(obj, a, value)

        def __delattr__(self, a):
            if a in attrs:
                traceback.print_stack()
            object.__delattr__(obj, a)

    Spy.__name__ = obj.__class__.__name__
    cls = obj.__class__
    obj.__class__ = Spy
    obj.__class__.__bases__ = (cls, )

    return obj