Question

Can I extend the constructor of the sueprtype? documentation doesnt say anything about extending functions.

I want to create a class which connects to a database when the subtypes are initialized but I don’t want to write a connection code for each subtype. So I’d like to do it in the constructor of the supertype but I also want subtypes to have constructors.

Answer 1

Yes, you can override the constructor just like any other method in a class:

<?php
class DbSuper {
    function __construct() {
        echo "db connection using super class<br/>";
    }
}

class DbSub extends DbSuper {
    function __construct() {
        echo "db connection using sub class<br/>";
    }
}

class DbSubNoConstr extends DbSuper {

}

class DbSubBothConstr extends DbSuper {
    function __construct() {
        echo "execute subclass code<br/>";
        parent::__construct();
    }

}

new DbSub(); //prints db connection using sub class
new DbSubNoConstr(); // prints db connection using super class
new DbSubBothConstr(); // prints execute subclass code db connection using super class
?>