Application of interfaces (interfaces, implements) in PHP object-oriented development

Application of interfaces (interfaces, implements) in PHP object-oriented development_PHP tutorial

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Release： 2016-07-13 10:50:16

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The application keywords of interfaces in PHP classes are interface and implements. An interface is a special abstract class whose member attributes are all abstract or constant. Let’s look at a few examples below.

Application of interfaces in classes

1. Keyword: interface
2. Keyword: implements

1. Introduction and creation of interfaces

Interface: A special abstract class whose member attributes are all abstract or constant.

Rules:

1. All methods in the class are abstract.
2. There is no need to add abstract to abstract methods.
3. The abstract method attribute of the interface is public.
4. Member attributes must be constants.

Format:

The code is as follows

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代码如下

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interface demo {
const NAME = "常量对象属性";

function fun1();
function fun2(); //抽象方法。
}

interface demo {

const NAME = "Constant object property";
function fun1(); function fun2(); //Abstract method.

}

2. Application and specification of interfaces

Interface references are different from class inheritance keyword extends. Inheritance can only be single, while interfaces can use the keyword implements to have multiple references separated by commas

1. Format: ordinary class reference interface

class MyPc implements demo , demo2 , demo3 {
...
}

2. Format: Abstract Class Application Interface Example

abstract class MyPc implements demo , demo2 , demo3 {
...
}

3. Format: Inherit the parent class reference interface and coexist

class MyPc extends Root implements demo , demo2 , demo3 {

...

}

Inherit first and then interface, single inheritance multiple interfaces.

4. Format: Interface and interface inheritance

代码如下

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interface demo {
const NAME = "名称";
function fun1();
function fun2();
}

interface demo2 {
function fun3();
function fun4();
}

interface demo3 {
const TEST = "Test";
function fun5();
}

class MyPc implements demo, demo2 {
function fun1() {
echo "++++++++++
";
}
function fun2() {
  echo "----------
";
}
function fun3() {
  echo "1111111111
";
}
function fun4() {
  echo "2222222222
";
}
}

class MyPs extends MyPc implements demo3 {
function fun5() {
echo "继承类后引用接口";
}
}
$p = new MyPs;
$p->fun1();
$p->fun2();
$p->fun3();
$p->fun4();
$p->fun5();
?>

interface demo3 extends demo { ... } Example:

The code is as follows	Copy code
"; } function fun2() { echo "---------- "; } function fun3() { echo "1111111111 "; } function fun4() { echo "2222222222 "; } } class MyPs extends MyPc implements demo3 { function fun5() { echo "Inherit the class and then reference the interface"; } } $p = new MyPs; $p->fun1(); $p->fun2(); $p->fun3(); $p->fun4(); $p->fun5(); ?>

Example

The interface is defined using the keyword interface, and the keyword implements is used to implement the methods in the interface, which must be fully implemented.

Example:

$display = new Goods(); $display ->run(new VipUser); //Can be more other user types

The code is as follows

代码如下

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//定义接口
interface User{
function getDiscount();
function getUserType();
}
//VIP用户接口实现
class VipUser implements User{
// VIP 用户折扣系数
private $discount = 0.8;
function getDiscount() {
return $this->discount;
    }
    function getUserType() {
        return "VIP用户";
    }
}
class Goods{
    var $price = 100;
    var $vc;
    //定义 User 接口类型参数，这时并不知道是什么用户
    function run(User $vc){
        $this->vc = $vc;
        $discount = $this->vc->getDiscount();
$usertype = $this->vc->getUserType();
        echo $usertype."商品价格：".$this->price*$discount;
    }
}

$display = new Goods();
$display ->run(new VipUser); //可以是更多其他用户类型
?>

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//Define interface

interface User{

Function getDiscount();

Function getUserType();

}

//VIP user interface implementation class VipUser implements User{ // VIP user discount coefficient

Private $discount = 0.8;

Function getDiscount() {

return $this->discount;

}
Function getUserType() {
return "VIP user";
}

}

class Goods{
var $price = 100; var $vc; //Define User interface type parameters, we don’t know what user it is at this time

Function run(User $vc){

$this->vc = $vc;
$discount = $this->vc->getDiscount();

$usertype = $this->vc->getUserType();

echo $usertype."Product price:".$this->price*$discount;
}
}

PHP can also implement multiple interfaces at the same time when inheriting a class:

class subclass extends parent class implemtns interface 1, interface 2, ...

{ … } 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: 1. 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. 2. 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 corresponding method name of its subclass will not be affected, but will change. It just becomes a new method (implemented relative to the old method). 3. Abstract classes can only be inherited singly. When a subclass needs to implement functions that need to be inherited from multiple parent classes, interfaces must be used. http://www.bkjia.com/PHPjc/632642.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632642.htmlTechArticleThe application keywords of the interface in the php class are interface and implements. An interface is a member whose attributes are all abstract or A special abstract class of constants. Let’s look at a few examples below. The application of the interface in the class...