Passing a class, or a totally different object, as the first argument to method is easy:
class Foo:
def method(self): ...
Foo.method(object()) # pass anything to self
I wonder, is this possible with classmethods as well? I assume it is, but how can it be done?
class Foo:
@classmethod
def cls_method(cls): ...
Foo.cls_method # how to pass cls=object
Related: hybrid / class_or_instance_method decorator / descriptor, but that is not a setting I am interested in.
On a very high level you could see the classmethod as a partial method that binds the first argument.
To be more precise when a function attribute, i.e. a method, is accessed its __get__ method kicks in.
For normal methods it transforms obj.f(*args) to f(obj, *args). If called from a class there is no extra argument injected. For classmethod it is a bit different as there is always a type injected: If called from an object: f(type(obj), *args), or if called from a class f(cls, *args) [1].
If you want to circumvent this you need to bypass the classmethod and access the function directly, you can do this via the __func__ attribute:
print(type(Foo.cls_method)) # method
print(type(Foo.cls_method.__func__)) # function
Foo.cls_method.__func__(object()) # no transformation, pass what you want
