playing with PHP 5.4

gistfile1.aw

<?php

class Container extends ArrayObject
{
}

trait ContainerAware
{
	private $container;

	public function setContainer(Container $container)
	{
		$this->container = $container;
	}

	public function get($name)
	{
		return $this->container[$name];
	}
}

class Guitar
{
	public function rock()
	{
		return 'CRAZY SHIT GUITAR SOLO!';
	}
}

class Rockstar
{
	use ContainerAware;

	public function getSongs()
	{
		return [
			'Smoke on the water',
			'Other shizzle',
		];
	}

	public function getOneSongLater()
	{
		return function ($i) {
			return $this->getSongs()[$i];
		};
	}

	public function rockTheGuitar()
	{
		return $this->get('guitar')->rock();
	}
}

$star = new Rockstar();
var_dump($star->getSongs()[0]);

$f = $star->getOneSongLater();
var_dump($f(1));

$container = new Container();
$container['guitar'] = new Guitar();
$star->setContainer($container);
var_dump($star->rockTheGuitar());

Did you omit the $i argument for Rockstar::getOneSongLater() ?

It's an argument to the closure, allowing you to specify it later - e.g. at closure call time.