PHP Static delayed static binding usage analysis_php skills

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 in 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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