PHP中如何形成static::与new static()的静态绑定

概述PHP中如何形成static::与new static()的静态绑定

PHP中static::与new static()之后期静态绑定

一、parent、self、$this、__CLASS__

class A {}class B extends A{parent::(public|protected)(静态方法|静态变量)  ===> parent永远是Aself::(public|protected)(静态方法|静态变量)  ===> self永远是B$this->(public|protected)(非静态方法|非静态变量)  ===> $this永远是B的是实例化对象__CLASS__    ===> 永远是B} class C extends B{parent::(public|protected)(静态方法|静态变量)  ===> parent永远是Bself::(public|protected)(静态方法|静态变量)  ===> self永远是C$this->(public|protected)(非静态方法|非静态变量)  ===> $this永远是C的是实例化对象__CLASS__    ===> 永远是C }

二、static::

static关键字可以实现以下功能：

1 调用类的静态方法 有后期静态绑定效果；

2 调用类的静态属性 有后期静态绑定效果；

3 调用类的非静态方法 没有后期静态绑定效果；

4 注意：不可以调用非静态属性；

class A {    private static function foo() {        echo "A success!\n";    }    public function test() {         $this->foo();    }} class B extends A {} class C extends A {    private static function foo() {    echo "C success!\n";    }} $b = new B();$b->test();//A success!$c = new C();$c->test();//A success!

class A {    private static function foo() {        echo "A success!\n";    }    public function test() {        static::foo();    }} class B extends A {} class C extends A {    private static function foo() {    echo "C success!\n";    }} $b = new B();$b->test();//A success!$c = new C();$c->test();//A无法调用C里的私有foo方法     //将C的foo改成非private(public|protected)就可以解决class A {    private static function foo() {        echo "A success!\n";    }    public function test() {        static::foo();    }} class B extends A {} class C extends A {    public static function foo() {    echo "C success!\n";    }} $b = new B();$b->test();//A success!$c = new C();$c->test();//C success!

class A { public static function foo() {     static::who(); }  public static function who() {     echo __CLASS__."\n"; }} class B extends A { public static function test() {     A::foo();     parent::foo();     self::foo(); }  public static function who() {     echo __CLASS__."\n"; }}class C extends B { public static function who() {     echo __CLASS__."\n"; } } C::test(); A =>A::foo()的结果C =>parent::foo()能走到A的foo,里面static::who找C::whoC =>self::foo()能走到B的foo,B继承A,走到A的foo,里面static::who找C::who     class A {    protected static function foo() {        static::who();    }     protected static function who() {        echo __CLASS__."\n";    }} class B extends A {    public static function test() {        A::foo();        parent::foo();        self::foo();    }     protected static function who() {        echo __CLASS__."\n";    }}class C extends B {    protected static function who() {        echo __CLASS__."\n";    } } C::test(); //A C C,解释同上     class A { public static function foo() {     static::who(); }  private static function who() {     echo __CLASS__."\n"; }} class B extends A { public static function test() {     A::foo();     parent::foo();     // self::foo();   }  private static function who() {     echo __CLASS__."\n"; }}class C extends B { private static function who() {     echo __CLASS__."\n"; } } C::test();//A =>A::foo()的结果 //报错 A不可C的私有方法who => parent::foo()能走到A的foo,里面static::who找C::who,C的who只能在C里调用，不能在A里调用//报错 A不可C的私有方法who => self::foo()能走到B的foo,B继承A,走到A的foo,里面static::who找C::who,C的who只能在C里调用，不能在A里调用

三、new static()

//new self()与new static()的区别，官网例子如下： class A {  public static function get_self() {    return new self();  }   public static function get_static() {    return new static();  }} class B extends A {} echo get_class(B::get_self()); // Aecho get_class(B::get_static()); // Becho get_class(A::get_static()); // A

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