decorator.php

<?php

class A {
	protected $kernel;


	public function handle() {
		print 1;
	}

	public function __construct() {
	}
}


class B {
	protected $kernel;


	public function handle() {
		$this->kernel->handle();
		// some extra logic;
		print 2;
	}

	public function __construct($kernel) {
		$this->kernel = $kernel;
	}
}

class C {
	protected $kernel;


	public function handle() {
		$this->kernel->handle();
		// some extra logic;
		print 3;
	}

	public function __construct($kernel) {
		$this->kernel = $kernel;
	}
}

$a = new A();

$a = new B($a);

$a = new C($a);

$a->handle(); // will print 123;