__call__ in Python

Python has a set of built-in methods and __call__ is one of them. The __call__ method enables Python programmers to write classes where the instances behave like functions and can be called like a function. When the instance is called as a function; if this method is defined, x(arg1, arg2, ...) is a shorthand for x.__call__(arg1, arg2, ...).

object() is shorthand for object.__call__()

Example 1:

class Example:
    def __init__(self):
        print("Instance Created")

    # Defining __call__ method
    def __call__(self):
        print("Instance is called via special method")

# Instance created
e = Example()

# __call__ method will be called
e()

Output :

Instance Created
Instance is called via special method

Example 2:

class Product:
    def __init__(self):
        print("Instance Created")

    # Defining __call__ method
    def __call__(self, a, b):
        print(a * b)

# Instance created
ans = Product()

# __call__ method will be called
ans(10, 20)

Output :

Instance Created
200