In Python there are a lot of built-in methods, including the infamous __main__ method. __call__ is another built-in method. The way it works is that it makes it possible to call an object like a function.

We're familiar with this code:

my_obj = Obj() // constructed

 

However did you know you can do this?

my_obj()

 

Yes. This is possible if we define the __call__ built-in method.

 

E.g.

class Obj():

    def __init__(self):
       print('init called')

    def __call__(self):

        print('use object as function')

 

> my_obj = Obj

init called

> my_obj()

use object as function