Singleton pattern

Singleton class is class that allow only one instance of its class to be instantiated.

A lot of examples I see the way to implement singleton pattern whether:

1. Extends a base singleton class
2. Each class apply singleton pattern (get_instance() method, has static $instance attribute)
3. Using registry pattern where one dedicated class act as the singleton instances manager

Well, things shouldn’t get too hard. Here, I will use the combination of registry pattern and singleton in just a function

function o($class) {
    static $instances;
    if (!isset($instances[$class]) || !$instances[$class] instanceof $class) {
        $instances[$class] =& new $class();
    }
    return $instances[$class];
}

To use it:

o('db')->query(...);
o('db')->fetch();
o('singleton_class')->do_something();

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Filed under Pelbagai with tags Idea, PHP, Registry pattern, Singleton

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