Detailed interpretation of the application of interfaces in PHP_php skills

Interface
PHP classes are single inheritance, that is, they do not support multiple inheritance. When a class requires the functions of multiple classes, inheritance is powerless. For this reason, PHP introduces interface technology

If all methods in an abstract class are abstract methods and no variables are declared, and all members in the interface have public permissions, then this special abstract class is called an interface

Interfaces are defined using the interface keyword, and implements are used to implement interface methods, which must be fully implemented

Implement an interface

The following is a practical example of PHP interface implementation. An interface named IPillage is created and implemented here. The IPillage interface is as follows:

interface IPillage
{
 function emptyBakAccount();
 function burnDocument();
}

Then implement this interface through the Executive class:

class Executive extends Employee implements IPillage
{
 private $totalStockOptions;
 function emptyBankAccount()
 {
  echo "Call CFO and ask to transfer funds to Swiss bank account.";
 }
 function burnDocuments()
 {
  echo "Torch the office suite.";
 }
}

Because people at all levels in the company can embezzle, there can be an Assistant class that implements this interface:

class Assistant extends Employee implements IPillage
{
 function takeMome()
 {
  echo "Taking memo...";
 }
 function emptyBankAccount()
 {
  echo "Go on shopping spree with office credit card.";
 }
 function burnDocuments()
 {
  echo "Start small fire in the trash can.";
 }
}

As you can see, the interface is particularly useful. Because, although they define how many methods are required to occur a certain behavior, as well as the names of each methods, interfaces allow different classes to implement these methods in different ways. In this example, for the method of burning files, the Assistdnt class just burns the files in the trash can, while the Executive class does it in a more extreme way (burning its office).

Implement multiple interfaces

It would be unfair if we allowed outside contractors to encroach on the company, after all the company was built with the efforts of all full-time employees. That is, how do you provide employees with jobs and encroach on company functions, while limiting contractors to only completing the required tasks? The solution is to break these tasks into several tasks and then implement the necessary multiple interfaces. PHPS supports this feature. Consider the following example:

<&#63;php
 interface IEmployee{...}
 interface IDeveloper{...}
 interface IPillage{...}
 class Employee implements IEmployee,IDeveloper,iPillage {
 ...
 }
 class Contractor implements IEmployee,IDeveloper {
 ...
 }
&#63;>

The difference between abstract classes and interfaces
An interface is a special abstract class, which can also be regarded as the specification of a model. The general differences between interfaces and abstract classes are as follows:

If a subclass implements an interface, it must implement all methods in the interface (whether needed or not); if it inherits an abstract class, it only needs to implement the required methods
If the method name defined in an interface changes, then all subclasses that implement this interface need to update the method name synchronously; and if the method name changes in an abstract class, the method name corresponding to its subclass will not be affected, but will become Just a new method
​​Abstract classes can only be inherited singly. When a subclass needs to implement functions that need to inherit from multiple parent classes, it must use interfaces

Code Example

 <&#63;php 
  
 /** 
  * 声明接口Demo 
  * @author wzy 
  * 
  */ 
 interface Demo 
 { 
  
  const NAME = "wangzhengyi"; 
  
  const AGE = 25; 
  
  function fun1 (); // 声明方法默认是public abstract 
  function fun2 (); 
 } 
  
 /** 
  * 声明接口的继承Demo2 
  * 
  * @author wzy 
  *   
  */ 
 interface Demo2 extends Demo 
 { 
  
  function fun3 (); 
  
  function fun4 (); 
 } 
  
 /** 
  * 声明接口Demo3 
  * 
  * @author wzy 
  *   
  */ 
 interface Demo3 
 { 
  
  function fun5 (); 
  
  function fun6 (); 
 } 
  
 /** 
  * 声明父类ParentClass 
  * 
  * @author wzy 
  *   
  */ 
 class ParentClass 
 { 
  
  function fun7 (); 
 } 
  
 /** 
  * 子类必须实现接口中所有的方法 
  * 
  * @author wzy 
  *   
  */ 
 class ChildClass extends ParentClass implements Demo2, Demo3 
 { 
  
  function fun1 (); 
  
  function fun2 (); 
  
  function fun3 (); 
  
  function fun4 (); 
  
  function fun5 (); 
  
  function fun6 (); 
 }