Python Coding challenge - Day 691| What is the output of the following Python Code?

 

Code Explanation:

1) Defining a Metaclass

class Meta(type):

Meta is a metaclass because it inherits from type.

Metaclasses are “classes of classes”, i.e., they define how classes themselves are created.

2) Overriding __new__

def __new__(cls, name, bases, dct):

__new__ is called when a class is being created, not an instance.

Parameters:

cls: the metaclass itself (Meta)

name: name of the class being created ("A")

bases: tuple of base classes (() in this case)

dct: dictionary of attributes defined in the class body

3) Modifying the Class Dictionary

dct["id"] = 99

Adds a new attribute id = 99 to the class dictionary before the class is created.

This means any class created with this metaclass will automatically have an id attribute.

4) Calling the Superclass __new__

return super().__new__(cls, name, bases, dct)

Calls type.__new__ to actually create the class object.

Returns the newly created class.

class A(metaclass=Meta):

    pass

5) Creating Class A

A is created using Meta as its metaclass.

During creation:

Meta.__new__ is called

dct["id"] = 99 is injected

A class object is returned

print(A.id)

6) Accessing the Injected Attribute

A.id → 99

The metaclass automatically added id to the class.

Output

99

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