decorator.php

<?php

interface Thing {
	public function execute();
}


	
class A implements Thing {
	public function execute()
	{
		var_dump('Core stuff is executing');
	}
}



class B implements Thing {
	public function __construct(Thing $thing)
	{
		$this->thing = $thing;
	}
	
	public function execute()
	{
		var_dump('class b is doing something');
		
		$this->thing->execute();
	}
}

class C implements Thing {
	public function __construct(Thing $thing)
	{
		$this->thing = $thing;
	}
	
	public function execute()
	{
		var_dump('class c is doing something');
		
		$this->thing->execute();
	}
}


(new B(new C(new A)))->execute();

/*
"class b is doing something"
"class c is doing something"
"Core stuff is executing"
*/