Classes and Objects

Abstract Classes

Abstract classes are classes that cannot be instantiated directly. They serve as blueprints for other classes (subclasses). They often contain one or more abstract methods, which are methods without a concrete implementation. Subclasses must provide implementations for these abstract methods.

Key features:

Abstract Methods: Defined using the @abstractmethod decorator from the abc (Abstract Base Classes) module. They have a signature but no body (or just a pass statement).
abc.ABC: The base class for creating abstract classes. Your abstract class should inherit from abc.ABC.
Enforcing Implementation: Abstract classes ensure that subclasses implement specific methods, promoting code consistency and preventing errors.

from abc import ABC, abstractmethod

class Shape(ABC):  # Inherits from abc.ABC, making it an abstract class
    @abstractmethod
    def area(self):
        pass  # No implementation in the abstract class

    @abstractmethod
    def perimeter(self):
        pass

class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14159 * self.radius * self.radius

    def perimeter(self):
        return 2 * 3.14159 * self.radius

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

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

    def perimeter(self):
        return 4 * self.side

#Trying to instantiate Shape will raise an error
#my_shape = Shape() #TypeError: Can't instantiate abstract class Shape with abstract methods area, perimeter

my_circle = Circle(5)
print(my_circle.area())
my_square = Square(4)
print(my_square.perimeter())

ABC Module (Method Overriding) Polymorphism

Abstract Classes

Carson West

Classes and Objects

Abstract Classes