Question

Can someone please explain what it means to have a class instance within the argument of another class instance:

$controller = new controllerObject(new dependenciesObject());

I understand the basics of classes and class instances but have never seen code like the above before. What does it mean? The controllerObect is a class so what does it mean to pass it an object instance in the argument?

Answer 1

All this means is that the controllerObject constructor accepts an object of type dependenciesObject.

You instantiate a dependenciesObject and use it as an argument to instantiate a controllerObject, which is assigned to $controller. If it helps you understand, this is equivalent to:

$dependency = new dependenciesObject();
$controller = new controllerObject($dependency);
unset($dependency);