PHP Static delayed static binding usage analysis, static_PHP tutorial

PHP Static delayed static binding usage analysis, static static

The example in this article describes the usage of PHP Static delayed static binding. Share it with everyone for your reference, the details are as follows:

After PHP5.3, delayed static binding static was introduced. What problem is it intended to solve? A long-standing problem with PHP's inheritance model is that it is difficult to reference the final state of an extended class in the parent class. Let’s look at an example.

class A 
{ 
  public static function echoClass(){ 
    echo __CLASS__; 
  }
  public static function test(){ 
    self::echoClass();    
  }
}
class B extends A 
{    
  public static function echoClass() 
  { 
     echo __CLASS__; 
  } 
} 
B::test(); //输出A

A new feature has been added to PHP5.3: delayed static binding, which means that expressions or variables that were originally fixed in the definition phase are changed to be determined in the execution phase. For example, when a subclass inherits a parent class When it is a static expression, its value cannot be changed. Sometimes you don't want to see this situation.

The following example solves the problem raised above:

class A 
{ 
  public static function echoClass(){ 
    echo __CLASS__; 
  } 
  public static function test() 
  { 
    static::echoClass();    
  } 
} 
class B extends A 
{    
  public static function echoClass(){ 
     echo __CLASS__; 
  } 
} 
B::test(); //输出B

static::echoClass(); on line 8 defines a static delayed binding method. The method that was originally defined will not be executed until B calls test.

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I hope this article will be helpful to everyone in PHP programming.

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