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Discuss in detail the difference between PHP static methods and ordinary methods

高洛峰
高洛峰Original
2016-12-20 16:44:23913browse

As shown below:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);
/*
普通方法,存放类内,只有一份
 
静态方法,也是存放于类内,只有一份
 
区别在于:普通方法需要对象去调用,需要绑定$this
即,普通方法,必须要有对象,然后让对象来调用
 
而静态方法,不属于哪一个对象,因此不需要绑定$this
即,不需要对象也可以调用
*/
 
class Human{
  static public $head=1;
  public function easyeat(){
    echo &#39;普通方法吃饭<br />&#39;;
  }
  static public function eat(){
    echo &#39;静态方法吃饭<br />&#39;;
  }
  public function intro(){
    echo $this->name;
  }
}
Error_reporting(E_ALL|E_STRICT);
//此时没有对象!方法可以执行
Human::eat();
/*
以下方法easyeat是一个非静态方法,就由对象来调用,但,用类来调用此方法来也可以执行,而严格状态下,此方法会执行,同时报错,
Strict Standards: Non-static method Human::easyeat() should not be called statically in D:\application\PHPnow-1.5.6\htdocs\yan18\types\staticfun.php on line 32
 
*/
Human::easyeat();
/*
接上,从逻辑来理解,如果用类名静态调用非静态(普通)方法
比如:intro()
那么,这个$this是指哪个对象呢??
因此会报错,因为找不到对象!
Fatal error: Using $this when not in object context in D:\application\PHPnow-1.5.6\htdocs\yan18\types\staticfun.php on line 23
*/
Human::intro();
 
/*
如上分析,其实,非静态方法,是不能由类名静态调用的,但目前,php中的面向对象检测不够严格,只要静态方法中没有$this关键字,就会转化成静态方法来处理!
*/
$li=new Human();
$li->eat();
 
/*
总结:
类》访问->静态方法(类的方法)->可以
类》访问->普通方法(对象的方法)->不可以(虽然方法里不用$this关键字时,可以!但不支持这种写法)
 
对象》访问》静态方法(类的方法)->可以
对象》访问》普通方法(对象的方法)->可以
 
*/
?>

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