Let's talk about the differences between interface methods of PHP classes

PHP is a popular programming language. In object-oriented programming, interface is a common concept. An interface in PHP means that a class defines a set of methods, but does not provide implementation. Instead, these methods are implemented by the class that implements the interface. Interfaces play the role of standardizing and constraining implementation classes, and have great flexibility and scalability. In PHP interface, it is divided into two types: abstract class interface and regular interface. In this article, we will focus on the differences between interface methods of PHP classes.

1. Abstract class interface

1. Abstract class definition

Abstract classes cannot be instantiated and can only be inherited. Its main function is It provides a basic structure for other classes. Common code is placed in abstract classes, and details are implemented in subclasses. Methods in abstract classes are optional, and some can be defined as abstract methods (that is, methods with only method names but no method bodies). An abstract class must contain at least one abstract method, otherwise all methods under its declaration will Considered a common method.

Example:

abstract class Animal{
   abstract function eat();
   function sleep(){
      echo "晚安，好梦！";
   }
}

2. Inheritance and implementation of abstract classes

Since abstract classes cannot be instantiated, they can only be implemented through subclasses. The class must implement all abstract methods defined in the abstract class, otherwise the subclass must also be defined as an abstract class.

Example:

class Cat extends Animal{
   function eat(){
      echo "吃小鱼干！";
   }
}

In the above code, we define a Cat class to inherit the Animal class, and at the same time Cat The eat() method is implemented in the class, so that we can access the specific implementation method in this abstract class through the Cat class.

3. Advantages of abstract classes

• Abstract classes can provide certain code reuse;
• Abstract classes can isolate the bottom layer of the system Implementation details, thereby reducing the coupling between modules;
• Abstract classes can provide consistent interfaces, allowing subclasses to standardize the implementation process when implementing specific functions.

2. Conventional interface

The conventional interface is another form of interface in PHP. Regular interfaces can have methods and constants. All methods defined in the interface must be implemented by any class, otherwise a fatal error will occur. By implementing a class of an interface, the class can access the methods and constants defined in the interface.

1. General interface definition

In PHP, we can define a regular interface and specify the methods that need to be implemented:

interface IAnimal{
   public function eat();
   public function run();
}

In this In the code snippet, we define an IAnimal interface and specify two methods that need to be implemented-eat() and run().

2. Implementation of conventional interfaces

When implementing a conventional interface, you must implement all the methods defined in it when implementing an interface, otherwise a compilation error will occur.

Example:

class Dog implements IAnimal{
   function eat(){
      echo "吃骨头！";
   }
   function run(){
      echo "追皮球！";
   }
}

In the above code snippet, we have defined a Dog class that implements the IAnimal interface and implemented it in There are two methods defined in the interface - eat() and run().

3. Advantages of conventional interfaces

• Conventional interfaces can improve the reusability of code;
• Conventional interfaces can reduce the coupling between codes degree, increasing code maintainability;
• Conventional interfaces can be implemented by multiple classes, and provide a unified interface to increase code scalability.

3. The difference between abstract class interface and conventional interface

1. Definition and use

How to define abstract class interface and conventional interface definition They are different. Abstract class interfaces are defined and implemented through abstract classes, while regular interfaces are defined and implemented directly.

Abstract class interfaces are implemented through inheritance, while regular interfaces are implemented by implementing all methods defined in the interface.

2. The difference between abstract classes and regular classes

Abstract classes can have ordinary methods and abstract methods, while regular interfaces can only define abstract methods;

Abstract classes must be implemented through inheritance, while regular interfaces can be implemented by multiple classes;

The abstract method of an abstract class must be implemented by subclasses, and any class that implements a regular interface must implement it in the same form All methods in the interface.

3. The difference in design semantics

Abstract class interfaces are mainly used to provide some common behaviors or data structure organization methods in language design. There can be an inheritance relationship or a combination relationship between an abstract class and its subclasses;

Conventional interfaces are mainly used to constrain the communication protocols between objects in the design of the language. Regular interfaces define some public specifications and methods, which are implemented by multiple classes.

Conclusion

Whether it is an abstract class interface or a regular interface, they are very important concepts in PHP. The abstract class interface can provide a flexible inheritance structure and support the default implementation of methods. It is recommended that the methods in the abstract class be common methods common between classes; while the conventional interface standardizes the method names of the class and it is recommended that the methods in the interface be specific between classes. task method. Therefore, when carrying out specific practical applications, we should choose different interface types according to specific usage scenarios.

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