Question

I have two classes that I use to access two different tables in my db. They both have a similar constructor that looks like that:

function __construct($db) {
    $this->db = $db;
    $userDAO = DAO_DBrecord::createUserDAO($this->db);
    $this->userDAO = $userDAO;
}

The other class has the same constructor except that it uses createOtherTableDAO($this->db).

I am planning on having a couple other such classes, and it would be convenient if I could have them all inherit the same constructor, and pass createAppropriateTableDAO as an argument.

To clarify, in the first case above, createUserDAO($this->db) is a static function that calls a constructor in my DAO class. The function in the DAO looks as follows:

public static function createUserDAO($db) {
    return new DAO_DBrecord($db, 'users');
}

I use this method to make sure the user model can only call a DAO on the users table.

I’m somewhat of a beginner, and I don’t think I have ever seen anything like what I want.

Answer 1

To answer your question first: No, you can’t (without resorting to evilCode) pass a function name as a parameter.
But: What you want to archive is a poster-child-issue for an object oriented approach using inheritance.

You’d need a base-class:

class BaseClass
{    
    function __construct($db) {
        $this->db = db;
    }    
}

and your implementations :

class MyClass extends BaseClass
{
    function __construct($db) {
        parent::__contruct($db);
        $this->userDAO = DAO_DBrecord::createUserDAO($this->db);
    }
}

Just for the record: the evilCode would have been
a) you could encapsulate your function in a create_function that can be used as an argument.
b) you could pass the function name as a string to your function and then pass it to eval in the receiving function.

But remember: When eval or create_function looks like the answer you’re probably asking the wrong questions!

See: related question