Python inheritance and polymorphism: from concept to application, all in one place

What is inheritance?

Inheritance is a basic concept in Object-orientedProgramming, which allows one class (subclass) to inherit the characteristics of another class (parent class). Subclasses inherit the properties and methods of the parent class and can override the parent class's methods to achieve different behaviors. This facilitates code reuse, reduces duplicate code and enhances scalability.

Inherited syntax

In python, use the class keyword to declare a subclass and specify the parent class. The following is the syntax:

class Subclass(Superclass):
# 子类代码

Polymorphism

Polymorphism means that an object can exhibit different behaviors depending on its type. In Python, polymorphism is mainly achieved through method coverage. When a subclass overrides a parent class method, the subclass object will use the overridden method, while the parent class object will still use the original method.

Advantages of polymorphism

• Enhance code readability and maintainability
• Promote code reuse
• Allows the creation of flexible and extensible programs

Implement polymorphism

In Python, polymorphism can be achieved by overriding parent class methods. Here are examples:

class Animal:
def make_sound(self):
print("Animal makes a sound.")

class Dog(Animal):
def make_sound(self):
print("Dog barks.")

class Cat(Animal):
def make_sound(self):
print("Cat meows.")

# 创建对象并调用方法
animal = Animal()
animal.make_sound()# 输出 "Animal makes a sound."

dog = Dog()
dog.make_sound()# 输出 "Dog barks."

cat = Cat()
cat.make_sound()# 输出 "Cat meows."

Advanced Inheritance Concept

• Multiple inheritance: A subclass can inherit multiple parent classes. Syntax: class Subclass(Superclass1, Superclass2, ...).
• Abstract class: A class that defines abstract methods (without implementation). Subclasses must override these abstract methods.
• Class methods: Methods that are bound to the class itself rather than to a specific object. Use the @cla<strong class="keylink">SSM</strong>ethod decorator declaration.
• Static method: A method that is not associated with a class or object. Use the @staticmethod decorator declaration.

Application scenarios

Inheritance and polymorphism are widely used in Python, including:

• Create reusable components and frameworks
• Implementing common interfaces between different types of objects
• Build flexible and scalable applications
• Simplify code maintenance and expansion

Conclusion

Inheritance and polymorphism are powerful tools in Python that can significantly enhance the reusability and scalability of your code. Understanding these concepts and applying them effectively to your code can help you write programs that are more flexible, easier to maintain, and more scalable.

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