Detailed introduction to relevant knowledge of class method rewriting in PHP

PHP is a powerful programming language. Through classes and objects, we can create some very powerful tools to process data and logic. Class method overriding is a very useful concept in PHP. Using it, we can redefine or extend existing methods in the class in a subclass. This article will introduce the relevant knowledge of class method rewriting in PHP in detail, and introduce readers to the specific implementation methods and usage techniques.

1. The concept of class method rewriting

Class method rewriting means that in the inheritance relationship, a subclass redefines or extends a method in the parent class. This is because some methods in the parent class cannot meet the needs of the subclass, so some methods need to be overloaded in the subclass and some new functions added to better complete the tasks of the subclass.

2. Implementation methods of class method rewriting

The implementation methods of class method rewriting can be roughly divided into the following two types:

1. Call the method through the parent class name

We can call the overridden method in the parent class in the subclass by using the parent class name. The sample code is as follows:

class ParentClass {
    public function printMessage() {
        echo 'This is a message from parent class.';
    }
}

class ChildClass extends ParentClass {
    public function printMessage() {
        echo 'This is a message from child class.';
        ParentClass::printMessage();
    }
}

We can see that in the subclass, we pass The method in the parent class is called using the name of the parent class, so that the original method in the parent class can still be used after overloading by the subclass.

2. Use the parent keyword to call the method

We can also use the keyword parent to call the overridden method in the parent class in the subclass. The sample code is as follows:

class ParentClass {
    public function printMessage() {
        echo 'This is a message from parent class.';
    }
}

class ChildClass extends ParentClass {
    public function printMessage() {
        echo 'This is a message from child class.';
        parent::printMessage();
    }
}

By using the parent keyword, we can call methods in the parent class, so that the methods of the subclass can not only contain the processing logic required by itself, but also have the original methods of the parent class.

3. Tips for using class method overriding

After understanding the implementation methods of class method rewriting, let’s introduce some tips for using class method overloading:

1. When rewriting a method, try to keep the original method signature as much as possible to avoid errors during the calling process.

2. When overloading a method in a subclass, try to maintain the calling type of the method. For example, if the method in the parent class is a public type, then it should also be when overloading in the subclass. public type.

3. When overloading methods in subclasses, follow the single responsibility principle as much as possible and encapsulate different functions into different methods to improve code readability and maintainability.

4. Summary

Class method rewriting in PHP is a very useful programming concept. Through method overloading, we can redefine or extend existing methods in the class in the subclass. method. This method can complete the reuse of functions very well and is also very common in large projects. However, in order not to affect subsequent use, we need to follow some usage tips as much as possible when overloading methods.

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