Who needs singletons?
- by sexyprout
Imagine you access your MySQL database via PDO. You got some functions, and in these functions, you need to access the database.
The first thing I thought of is global, like:
$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'root', 'pwd');
function some_function() {
global $db;
$db->query('...');
}
But it's considered as a bad practice. So, after a little search, I ended up with the Singleton pattern, which "applies to situations in which there needs to be a single instance of a class."
According to the example of the manual, we should do this:
class Database {
private static $instance, $db;
private function __construct(){}
static function singleton() {
if(!isset(self::$instance))
self::$instance = new __CLASS__;
return self:$instance;
}
function get() {
if(!isset(self::$db))
self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd')
return self::$db;
}
}
function some_function() {
$db = Database::singleton();
$db->get()->query('...');
}
some_function();
But I just can't understand why you need that big class when you can do it merely with:
class Database {
private static $db;
private function __construct(){}
static function get() {
if(!isset(self::$rand))
self::$db = new PDO('mysql:host=127.0.0.1;dbname=toto', 'user', 'pwd');
return self::$db;
}
}
function some_function() {
Database::get()->query('...');
}
some_function();
This last one works perfectly and I don't need to worry about $db anymore.
But maybe I'm forgetting something. So, who's wrong, who's right?
