An in-depth analysis of the implementation of multiple inheritance in Python

Detailed explanation of Python multiple inheritance implementation methods

In Python, multiple inheritance is a common programming technique that allows a class to inherit properties from multiple parent classes. and methods. This article will introduce in detail the implementation method of multiple inheritance in Python, with specific code examples.

1. Use multiple parent classes separated by commas

In Python, we can use multiple parent classes separated by commas to implement multiple inheritance. Subclasses inherit the properties and methods of each parent class. The following is a simple example:

class Parent1:
    def parent1_method(self):
        print("This is Parent1 method.")

class Parent2:
    def parent2_method(self):
        print("This is Parent2 method.")

class Child(Parent1, Parent2):
    pass

child = Child()
child.parent1_method()   # 输出：This is Parent1 method.
child.parent2_method()   # 输出：This is Parent2 method.

In this example, the Child class inherits Parent1 and Parent2 using comma separation. A parent class, thus owning their properties and methods.

2. Method parsing order

When a subclass inherits multiple parent classes, the order in which methods are called is regular. Python uses the C3 linearization algorithm to determine the parsing order of methods. This algorithm ensures that there will be no confusion or conflict in the order of method calls.

For example, if the method names of Parent1 and Parent2 are the same, then when the method is called in the subclass, the method of the parent class inherited first will be executed first. . Here is an example:

class Parent1:
    def method(self):
        print("This is Parent1 method.")

class Parent2:
    def method(self):
        print("This is Parent2 method.")

class Child(Parent1, Parent2):
    pass

child = Child()
child.method()   # 输出：This is Parent1 method.

In this example, Child inherits the method method of Parent1 and Parent2 . Since Parent1 is earlier in the inheritance order, its methods will be called first by subclasses.

3. Usage of super() function

The super() function is a method used to call the parent class. It can specify which parent class method to call in the case of multiple inheritance. The following is an example of using the super() function:

class Parent1:
    def method(self):
        print("This is Parent1 method.")

class Parent2:
    def method(self):
        print("This is Parent2 method.")

class Child(Parent1, Parent2):
    def method(self):
        super().method()
        print("This is Child method.")

child = Child()
child.method()

In this example, the method method in Child is called through super().method() Parent1 method. In this way, the methods of the parent class can be extended in the subclass.

4. Diamond Problem (Diamond Inheritance Problem)

The diamond inheritance problem refers to when a subclass inherits two parent classes with a common parent class at the same time, it will Leading to ambiguity in method calls. In order to solve this problem, Python uses the C3 linearization algorithm to ensure the uniqueness of the method parsing order.

The following is a simple example:

class Grandparent:
    def method(self):
        print("This is Grandparent method.")

class Parent1(Grandparent):
    def method(self):
        print("This is Parent1 method.")

class Parent2(Grandparent):
    def method(self):
        print("This is Parent2 method.")

class Child(Parent1, Parent2):
    pass

child = Child()
child.method()  # 输出：This is Parent1 method.

In this example, Child inherits two parent classes that have a common parent class Parent1 and Parent2. Due to the inheritance order, the methods in Parent1 will be called first.

Summary:

This article introduces in detail the implementation method of multiple inheritance in Python. Multiple inheritance can be achieved by using multiple parent classes separated by commas. The method parsing order follows the C3 linearization algorithm, and the super() function is used to call the parent class's method. Although multiple inheritance can bring a more flexible programming style, you also need to pay attention to the ambiguity of solving the diamond inheritance problem. Being proficient in the use of multiple inheritance will enable us to better program in Python.

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