CODEWITHSUNDEEP
phpclassinheritance
stef
stef

Reputation: 470

PHP object inheritage from class constructor - the right way

I need some guidance about an php object inheritage situation. I have: a configuration object like:

configuration{
    var driver = 'mysql'; // or 'mssql';
    var host = 'database_host';
    var user = 'database_user';
    var password = 'database_password';
    var name = 'database_name';
}

two database handler classes:

class mysql{
    public mysql(){} // connect
    public query(){} // set a query
    public result(){} // load result
}

class mssql{
    public mysql(){} // connect
    public query(){} // set a query
    public result(){} // load result
}

and some kind of class controller:

class database{
    public function __construct(){
        $configuration = new configuration;
        /*
         * now, depending on the value of the $configuration->driver
         * my database class must inherit methods from mysql or mssql class
         */
        switch( $configuration->driver ){
            case 'mysql':
                // database inherit mysql methods
            break;
            case 'mssql':
            // database inherit mssql methods
            break;
        }
    }
}

usage like:

$database = new database;
$database->query( 'select * from some_table' );
$result = $database->result();

so, when I use my database class methods, depending on configuration object, I actually use mysql or mssql methods. the way i see it is not passible because I want my database class to inherit another class in the class constructor.

I was hoping that someone could give me an advice about how can I do this.. let's say.. the right way.

Thanks.

Upvotes: 0

Views: 154

Answers (2)

stef
stef

Reputation: 470

If someone, as confusend as me, reads this post, this is the solution I found (after weeks of research - yes, after weeks):

using singleton pattern, create a parent class called database:

class database{
    protected static $instances = array();

    // method to create a new instance of this object
    public function getInstance( $driver ){
        $instanceid = md5( $driver );

        if( self::$instances[ $instanceid ] == null ){
            self::$instances[ $instanceid ] = new $driver;
        }

        return self::$instances[ $instanceid ];
    }

    public function testFunction(){
        //do something else
    }
}

then create driver functions

class mysql extends database{
    public mysql(){} // connect
    public query(){} // set a query
    public result(){} // load result
}

class mssql extends database{
    public mysql(){} // connect
    public query(){} // set a query
    public result(){} // load result
}

now use it like

$database = database::getInstance( 'mysql' );
$database->query(); // works
$database->testFunction(); // works to

and further on you can use and like

$database = database::getInstance( 'mssql' );
$database->query(); // works
$database->testFunction(); // works to

I need to apologize to Froncoise for unchecking his answer as the right one.

Upvotes: 0

Francois Bourgeois
Francois Bourgeois

Reputation: 3690

nonono, this is not oop-thinking. You should google the following keywords:

When you did, put the switch statement into the factory, make the class mysql an interface named DBDriver, and use the strategy pattern in your database class.

Upvotes: 1

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