mysql - PHP: Calling a method on a class property that is an object -

can let me know if practice or if there better cleaner way it? looks clumsy me, i'm wondering if there's reason haven't seen before.

class {   public $instance_of_b;    function __construct () {     $this->instance_of_b = new b;   }    function deeper_hello() {     $this->instance_of_b->say_hi();   } }  class b {   public function say_hi() {     echo "hello, b!";   }  }  $instance_of_a = new a; $instance_of_a->deeper_hello(); 

it parses php it's not semanticly wrong, there cleaner way of doing it?

i should say, not code, it's method. i'm doing creating sql class uses pdo. in sql class, i'm recording pdo , pdostatment objects in properties of sql class.

rather instantiating b inside of a, better pass b via constructor. called dependency injection , doing no longer tightly coupled b.

class {   public $instance_of_b;    function __construct ($b) {     $this->instance_of_b = $b;   }    function deeper_hello() {     $this->instance_of_b->say_hi();   } }  class b {   public function say_hi() {     echo "hello, b!";   }  }  $instance_of_b = new b; $instance_of_a = new a($instance_of_b); $instance_of_a->deeper_hello();