[php] Creating a config file in PHP

You can create a config class witch static properties

class Config 
{
    static $dbHost = 'localhost';
    static $dbUsername = 'user';
    static $dbPassword  = 'pass';
}

then you can simple use it:

Config::$dbHost  

Sometimes in my projects I use a design pattern SINGLETON to access configuration data. It's very comfortable in use.

Why?

For example you have 2 data source in your project. And you can choose witch of them is enabled.

• mysql
• json

Somewhere in config file you choose:

$dataSource = 'mysql' // or 'json'

When you change source whole app shoud switch to new data source, work fine and dont need change in code.

Example:

Config:

class Config 
{
  // ....
  static $dataSource = 'mysql';
  / .....
}

Singleton class:

class AppConfig
{
    private static $instance;
    private $dataSource;

    private function __construct()
    {
        $this->init();
    }

    private function init()
    {
        switch (Config::$dataSource)
        {
            case 'mysql':
                $this->dataSource = new StorageMysql();
                break;
            case 'json':
                $this->dataSource = new StorageJson();
                break;
            default:
                $this->dataSource = new StorageMysql();
        }
    }

    public static function getInstance()
    {
        if (empty(self::$instance)) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    public function getDataSource()
    {
        return $this->dataSource;
    }
}

... and somewhere in your code (eg. in some service class):

$container->getItemsLoader(AppConfig::getInstance()->getDataSource()) // getItemsLoader need Object of specific data source class by dependency injection

We can obtain an AppConfig object from any place in the system and always get the same copy (thanks to static). The init () method of the class is called In the constructor, which guarantees only one execution. Init() body checks The value of the config $dataSource, and create new object of specific data source class. Now our script can get object and operate on it, not knowing even which specific implementation actually exists.