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A self::( 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B self::( 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::who C =>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()); // A echo get_class(B::get_static()); // B |