Monkey patching a @property

Question

Is it at all possible to monkey patch the value of a @property of an instance of a class that I do not control?

class Foo:
    @property
    def bar(self):
        return here().be['dragons']

f = Foo()
print(f.bar)  # baz
f.bar = 42    # MAGIC!
print(f.bar)  # 42

Obviously the above would produce an error when trying to assign to f.bar. Is # MAGIC! possible in any way? The implementation details of the @property are a black box and not indirectly monkey-patchable. The entire method call needs to be replaced. It needs to affect a single instance only (class-level patching is okay if inevitable, but the changed behaviour must only selectively affect a given instance, not all instances of that class).

Answer 1

Subclass the base class (Foo) and change single instance's class to match the new subclass using __class__ attribute:

>>> class Foo:
...     @property
...     def bar(self):
...         return 'Foo.bar'
...
>>> f = Foo()
>>> f.bar
'Foo.bar'
>>> class _SubFoo(Foo):
...     bar = 0
...
>>> f.__class__ = _SubFoo
>>> f.bar
0
>>> f.bar = 42
>>> f.bar
42