t.php

<?php
$container['pdo'] = function ($C) {return new Pdo(..);}
$container['B'] = function ($c) {return new B($c['pdo']);} // pass in the dependency
$container['C'] = function ($c) {return new C($c['B']);}

class B {
  function __construct(\PDO $a){}
}
class C {
  function __construct(B $b){}
}

// i want to use class C
$c = $container['C'];