pass an object to another object constructor in PHP

Question

I am reading about design patterns in PHP and I keep seeing the following syntax, for example

$newClass = new myClass(new myOtherClass());

I guess that this passes some kind of a myOtherClass reference inside myClass , so here

class myClass{

    private $myOtherClass;

    public function __construct(myOtherClass $myOtherClass) {
        $this->myOtherClass= $myOtherClass;
    }

    public function myClassMethod($var) {
        $this->myOtherClass->methodOfMyOtherClass($var);
    }
}

the construct refers to myOtherClass and I can use the methodOfMyOtherClass of myOtherClass from the myClass myClassMethod , like so $newClass->myClassMethod('a value here');

My questions are :

What is the name of that practice?

Did I got the concept right?

Where can I read more about it?

(first time I saw this syntax is here , this is where I also based my code for this question)

Answer 1

What is the name of that practice?
Typically this is called Dependency Injection . myClass required myOtherClass in order to properly execute it's methods, so myOtherClass is a dependency of myClass . Read more here .

Did I got the concept right?
It looks like you have the concept right. At least based on your sample, you are using it correctly.

Where can I read more about it?
If you want to read more about Dependency Injection only, I recommend this . In general, the principles taught by the 12 Factor App are very good and are worth reading about. 12 Factor App .

Some good books worth reading along these lines:
Clean Code
Patterns for Enterprise Architecture