家长在孩子最佳实践中的PHP调用函数

Question

I have a trick question regarding PHP calling a function from parent in child class. We have 3 scenarios, and I want pros and cons.

<?php
class test{
   private $var ;
   public function __construct(){
    $this->var = 'Hello world';
   }

   public function output(){
      echo $var.'<br>';
   }
}
//scenario 1
class test1 extends test{
   public function __construct(){
    parent::__construct();
   }
   public function say(){
    parent::output();
   }
}
//scenario 2
class test2 extends test{
   public function __construct(){
    test::__construct();
   }
   public function say(){
    test::output();
   }
}
//scenario 3
class test3 extends test{
    private $handle ;
    public function __construct(){
     $this->handle = new test();
    }
    public function say(){
     $this->handle->output();
    }
}
//finally I can call any 3 cases by one of the below codes
$test1 = new test1();
$test1->say();
//or
$test2 = new test2();
$test2->say();
//or
$test3 = new test3();
$test3->say();
?>

Is there a best practice or is there any of the 3 scenarios better than other?

Thank you in advance.

Answer 1

1) Is correct

2) Is incorrect call the method like a static method.

3) It does not have any sense extend and create in the constructor.

Answer 2

1) This one is correct, as its calling the parent from its methods.

class test1 extends test{
   public function __construct(){
    parent::__construct();
   }
   public function say(){
    parent::output();
   }
}

2) The inheritance in here is unnecessary. If you choose this implementation, you must change both output and construct method to static.

//scenario 2
class test2 extends test{
   public function __construct(){
    test::__construct();
   }
   public function say(){
    test::output();
   }
}

3) The inheritance from here is also unnecessary. Note here you are using "component over inheritance" pattern which is a good practice as it provides more flexibility, but you must delete the "extends test".

//scenario 3
class test3 extends test{
    private $handle ;
    public function __construct(){
     $this->handle = new test();
    }
    public function say(){
     $this->handle->output();
    }
}