gistfile1.txt

class MathIsFun {
	private $someInterface = null;
	public function __construct(iSomeInterface $dependency) {
		$this->someInterface = $dependency;
	}
	public function add($number=0) {
		return $number + $this->someInterface->getNumber();
	}
}

// vs

class MathIsFun {
	public function add(iSomeInterface $dependency, $number=0) {
		return $number + $dependency->getNumber();
	}
}