Final in PHP

Final Chinese meaning is "last, final", can modify the class or method.

1) When you do not want a method of a parent class to be overloaded (override), you can modify it with the final keyword

2 When you do not want the class to be inherited, you can use the final modifier

Format:

Final Class class Name {

}

Class Name {

Final modifier function name (argument list) {}

}

1, if you want a class not to be inherited by other classes, you can use the final

Cases:

<?php
  Final class a{
  }
  Class B extends a{//will have an error
  }
  echo "OK";
?>

2. If you want a method that is not overridden by any subclass, such as a method of calculating personal income tax, you can use final to modify the method.

<?php
  Class a{
     Final public Function getrate ($salary) {
        return $salary *0.08;
     }
  }
  
     Public Function Getrate ($salary) {
        return $salary *0.01;
     }
  }
  $b =new B ();
  echo $b->getrate (2000); The runtime will complain because the getrate () in parent Class A is using the final decoration and cannot be overridden in a subclass
?>

3, by the final modified method, you can inherit the quilt class, but cannot override the quilt class

Cases:

<?php
  Class a{
     Final public Function getrate ($salary) {
        return $salary *0.08;
     }
  }
  
     /*public function Getrate ($salary) {
        return $salary *0.01;
     }*/
  }
  $b =new B ();
  echo $b->getrate (2000); Output 160
?>

4, the final keyword can not modify attributes (variables)

Url:http://www.bianceng.cn/webkf/php/201612/50493.htm