PHP中static::与new static()之后期静态绑定
一、parent、self、$this、__CLASS__
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class A {}class B extends A{parent::(public|protected)(静态方法|静态变量) ===> parent永远是Aself::(public|protected)(静态方法|静态变量) ===> self永远是B$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；大理石构件维修厂家
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；
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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! |
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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! |
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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()
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//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()); // B |
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