Python Anonymous Classes and Objects: Using the type() Function

Explore Python's type() function to determine the class of an object. Learn how both built-in and user-defined classes are identified as objects of type class, with practical examples demonstrating its usage.

Python - Anonymous Class and Objects

Introduction

Python's type() function returns the class that an object belongs to. Both built-in and user-defined classes are objects of type class.

Example

Here's an example demonstrating how to use type():

class MyClass:
    def __init__(self):
        self.myvar = 10

obj = MyClass()

print('class of int', type(int))
print('class of list', type(list))
print('class of dict', type(dict))
print('class of MyClass', type(MyClass))
print('class of obj', type(obj))
        

class of int 
class of list 
class of dict 
class of MyClass 
class of obj 
        

Creating an Anonymous Class

We can dynamically create a class using the three-argument version of the type() function:

newclass = type(name, bases, dict)
        

Arguments:

• name: Name of the class, becomes __name__ attribute.
• bases: Tuple of parent classes, can be empty if not a derived class.
• dict: Dictionary forming the namespace of the new class containing attributes and methods.

To create an anonymous class:

anon = type('', (object,), {})
        

Creating an Anonymous Object

To create an object of the anonymous class:

obj = anon()
print("type of obj:", type(obj))
        

type of obj: 
        

Adding Instance Variables and Methods Dynamically

We can add instance variables and methods to the anonymous class dynamically:

def getA(self):
    return self.a

obj = type('', (object,), {'a': 5, 'b': 6, 'c': 7, 'getA': getA, 'getB': lambda self: self.b})()
print(obj.getA(), obj.getB())
        

5 6