Design Patterns: How to create database object/connection only when needed?

Question

I\'ve a simple application, say it has some classes and an \"extra\" one that handles database requests. Currently i\'m creating the database object everytime the app is use

Answer 1

You could use an singleton pattern to achive this and request everytime you need the database a database object. This results in something like this

$db = DB::instance();

where DB::instance is declared something like this

class DB {

    //...

    private static $instance;    

    public static function instance() {
        if (self::$instance == null) {
            self::$instance = new self();
        }
    }

    //...

}