Explore how to implement multiple inheritance in Python

In-depth understanding of the implementation of multiple inheritance in Python

In Python, multiple inheritance is a powerful feature that allows a class to inherit from multiple parent classes Properties and methods. Multiple inheritance is very useful in object-oriented programming and can help us reuse code and organize functions efficiently.

Python uses the C3 algorithm to solve the problem of method calling order in multiple inheritance. This algorithm will maintain the depth priority of methods and avoid conflicts between classes. Below we will learn three ways to implement multiple inheritance and illustrate them with specific code examples.

1. Traditional method
   The traditional method refers to multiple parent classes separated by commas directly in the class declaration. The following is a simple example:

class Parent1:
    def hello(self):
        print("Hello from Parent1")

class Parent2:
    def hello(self):
        print("Hello from Parent2")

class Child(Parent1, Parent2):
    pass

c = Child()
c.hello()

The output result is:

Hello from Parent1

In this example, the Child class inherits the hello methods of the two parent classes, Parent1 and Parent2. When the hello method is called, Python will search the parent class from left to right in the order of inheritance, and the first method that meets the conditions will be executed.

2. Using the super function
   In addition to the traditional method, we can also use the super function to implement multiple inheritance. The super function can automatically find the next qualified method and return it to the subclass for calling. The following is a sample code:

class Parent1:
    def hello(self):
        print("Hello from Parent1")

class Parent2:
    def hello(self):
        print("Hello from Parent2")

class Child(Parent1, Parent2):
    def hello(self):
        super().hello()  # 调用父类的hello方法

c = Child()
c.hello()

The output is:

Hello from Parent1

In this example, the Child class calls the hello method of the parent class by calling super().hello(). The super function will search for qualified methods starting from the next parent class of the current class.

3. Using the Mixin class
   The Mixin class is a special class, which is mainly used to store shared properties and methods and can be inherited by multiple classes. Mixin classes usually do not contain initialization methods, only some specific functions. The following is an example:

class Mixin1:
    def hello(self):
        print("Hello from Mixin1")

class Mixin2:
    def hello(self):
        print("Hello from Mixin2")

class Child(Mixin1, Mixin2):
    pass

c = Child()
c.hello()

The output is:

Hello from Mixin1

In this example, the Child class inherits the two Mixin classes Mixin1 and Mixin2, which provide the hello method. When the hello method is called, Python will search the Mixin class from left to right in inheritance order, and the first method that meets the conditions will be executed.

Comparing these three implementation methods, the traditional method is simple and direct, but prone to method conflicts; using the super function can avoid method conflicts, but may change the original calling logic; using the Mixin class can achieve code duplication Use it, but you need to pay attention to the inheritance order of Mixin classes.

It should be noted that in actual development, multiple inheritance should be used with caution, especially when there are method conflicts between parent classes. Properly inheriting the parent class and taking advantage of many inherited features can make the code more concise, flexible and efficient.

Summary
In this article, we took an in-depth look at how multiple inheritance is implemented in Python. Through the traditional method, using the super function and using the Mixin class, we can choose the appropriate way to inherit multiple parent classes according to different needs. These implementation methods give us flexibility and help us organize code and implement functions efficiently. When using multiple inheritance, you need to pay attention to the calling order of methods and possible conflicts to ensure the correctness and maintainability of the code.

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