Python Inheritance and Polymorphism: The Way to Advance to Create Excellent Code

Inheritance in Python

Inheritance is one of the core Object-orientedProgramming concepts in python. It allows new classes (subclasses) to inherit from existing classes (parent classes). ) inherits properties and methods. Through inheritance, subclasses can reuse the functions of the parent class and extend them on this basis, thereby achieving code reuse and decoupling.

Creation of subclasses

To create a subclass, you need to use the keyword class, followed by the name of the subclass and the name of the parent class, separated by a colon. For example:

class ChildClass(ParentClass):
# 子类特有的属性和方法

Method overriding

Subclasses can override methods in the parent class to achieve their own specific behavior. When overriding a parent class method, you only need to define a method with the same name and parameters in the child class. For example:

class ParentClass:
def print_message(self):
print("Parent class message")

class ChildClass(ParentClass):
def print_message(self):
print("Child class message")

Polymorphism

Polymorphism means that the same message can produce different behaviors according to different objects. In Python, polymorphism can be achieved through inheritance and method overriding.

Abstract method of parent class

The parent class can define abstract methods. These methods do not have any implementation, but are implemented by subclasses. The declaration of abstract methods requires the use of the @abstractmethod decorator. For example:

from abc import ABC, abstractmethod

class ParentClass(ABC):
@abstractmethod
def do_something(self):

Subclass polymorphic implementation

When a subclass implements an abstract method, it must use the super() function to explicitly call the method of the parent class to ensure that the method of the parent class is called correctly. For example:

class ChildClass(ParentClass):
def do_something(self):
super().do_something()
# 子类特有的操作

Polymorphic application scenarios

Polymorphism is widely used in object-oriented programming. Common scenarios include:

• Event handling in GUI applications, different types of GUI controls can respond to the same events, but produce different behaviors.
• DatabaseAccess, different Database connection objects can execute the same query, but produce different database operations.
• Data structureProcessing, different data structures can achieve the same operation, but have different storage and retrieval methods.

Advanced skills in Python inheritance and polymorphism

• Combination of composition and inheritance: In some cases, composition is more appropriate than inheritance. Composition allows objects to contain references to other objects without inheriting their properties or methods.
• Abstract class: Abstract classes cannot be instantiated, but abstract methods can be defined and implemented by subclasses. Abstract classes are mainly used to define interfaces and force subclasses to provide certain functions.
• Multiple inheritance: Python supports multiple inheritance, allowing a class to inherit from multiple parent classes. Multiple inheritance needs to be used with caution to avoid the diamond problem in the inheritance tree.
• Metaclass: Metaclass controls the creation process of a class and can realize the behavior of dynamically creating and modifying classes. Metaclasses are mainly used for advanced scenarios, such as creating singleton classes or implementing ORMframework.

in conclusion

Inheritance and polymorphism in Python are key concepts in object-oriented programming, and understanding and mastering them is crucial to writing reusable, extensible, and maintainable code. Through the in-depth explanation and code examples of this article, I hope readers can master these concepts and apply them to actual programming projects to create code excellence.

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