I once read that static classes are very difficult and even impossible to debug. Is this true and why?
If an example would help, here is a PHP class I use to access a database (I don't think this is a PHP-specific question, though):
<?php
class DB
{
private static $instance;
private function __construct() { }
public static function getInstance()
{
if(!self::$instance)
{
self::$instance = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME . ';', DB_USER, DB_PASS);
}
return self::$instance;
}
public static function getPreparedStatement($query)
{
$db = self::getInstance();
return $db->prepare($query);
}
public static function query($query)
{
$stmt = self::getPreparedStatement($query);
$stmt->execute();
}
public static function getResult($query)
{
$stmt = self::getPreparedStatement($query);
$stmt->execute();
return $stmt;
}
public static function getSingleRow($query)
{
$stmt = self::getPreparedStatement($query);
$stmt->execute();
return $stmt->fetch();
}
public static function getMultipleRows($query)
{
$stmt = self::getPreparedStatement($query);
$stmt->execute();
return $stmt->fetchAll();
}
}
?>