What is the purpose of the @abstractmethod decorator in Python?

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Answer:

The @abstractmethod decorator in Python is used to define abstract methods for abstract base classes. An abstract method is a method that is declared, but not defined, in the abstract base class. Subclasses of the abstract base class are required to implement the abstract methods, which ensures that they conform to a certain interface.

The @abstractmethod decorator is used to indicate that a method is abstract. The abstract method must be overridden by any subclass of the abstract base class, otherwise a TypeError will be raised.

For example, consider the following code:

from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

class Square(Shape):
    def __init__(self, side):
        self.side = side

    def area(self):
        return self.side ** 2

In this example, the Shape class defines an abstract method area, which is not implemented in the abstract base class. The Square class is a concrete subclass of Shape, and it provides an implementation of the area method.

When a subclass of an abstract base class is defined, any abstract methods in the abstract base class must be overridden by the subclass. If a subclass does not override an abstract method, a TypeError will be raised at runtime. This ensures that all subclasses of the abstract base class conform to a certain interface.

By using the @abstractmethod decorator, the Shape class can define an abstract method area, which is required to be implemented by any subclass of Shape. This makes the code more maintainable and helps to prevent programming errors by enforcing that any subclass of Shape must implement the area method.

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