Is it safe just use __class__ in a python class definition

Question

I understand __class__ can be used to get the class of an object, it also can be used to get current class in a class definition. My question is, in a python class definition, is it safe just use __class__, rather than self.__class__?

#!/usr/bin/python3

class foo:
    def show_class():
        print(__class__)

    def show_class_self(self):
        print(self.__class__)


if __name__ == '__main__':
    x = foo()
    x.show_class_self()
    foo.show_class()

./foo.py
<class '__main__.foo'>
<class '__main__.foo'>

As the codes above demonstrated, at least in Python3, __class__ can be used to get the current class, in the method show_class, without the present of "self". Is it safe? Will it cause problems in some special situations? (I can think none of it right now).

Answer 1

That is documented in the datamodel, so I believe it is safe/reliable.

From 3.3.3.5. Executing the class body:

Class variables must be accessed through the first parameter of instance or class methods, or through the implicit lexically scoped __class__ reference described in the next section.

From 3.3.3.6. Creating the class object:

__class__ is an implicit closure reference created by the compiler if any methods in a class body refer to either __class__ or super

It is true that the docs mention any methods, your foo.show_class is a function but perhaps not convincingly a method. However PEP 3135, which added this reference, is worded differently:

Every function will have a cell named __class__ that contains the class object that the function is defined in. ... For functions defined outside a class body, __class__ is not defined, and will result in runtime SystemError.