Referencing other classes in a class - php

Question

Say I have two php classes - class Security and class Database

Security

class Security {
    public function userPermissions() {
        //use getData() from Database to obtain information 
    }
}

Database

class Database { 
    public function getData() {
        // some code 
        }
    }

The security class needs to get data using the database class, there are many ways of achieving this but am not sure of best practice.

Is it better to do create an instance of both like;

$db = new Database;
$sec = new Security($db);

and then in the Security class use a constructor to pass the instance of the db to it?

Or would you create a new instance in the __constructor method within the security class?

I'd be grateful for any best practice.

Answer 1

Create an instance of both and then in the Security class use a constructor to pass the instance of the db to it

The approach you described is called Dependency injection and it is generally better solution for your case from the architectural point of view.