Question

I’m trying to build site using OOP in PHP. Everyone is talking about Singleton, hermetization, MVC, and using exceptions. So I’ve tried to do it like this:

Class building whole site:

class Core
{
    public $is_core;
    public $theme;
    private $db;
    public $language;
    private $info;
    static private $instance;

    public function __construct($lang = 'eng', $theme = 'default')
    {
        if(!self::$instance)
        {
            try
            {
                $this->db = new sdb(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS);
            }
            catch(PDOException $e)
            {
                throw new CoreException($e->getMessage());
            }
            try
            {
                $this->language = new Language($lang);
            }
            catch(LangException $e)
            {
                throw new CoreException($e->getMessage());
            }
            try
            {
                $this->theme = new Theme($theme);
            }
            catch(ThemeException $e)
            {
                throw new CoreException($e->getMessage());
            }
        }
        return self::$instance;
    }
    public function getSite($what)
    {
        return $this->language->getLang();
    }
    private function __clone() { }

}

Class managing themes

class Theme
{
    private $theme;
    public function __construct($name = 'default')
    {
        if(!is_dir("themes/$name"))
        {
            throw new ThemeException("Unable to load theme $name");
        }
        else
        {
            $this->theme = $name;
        }
    }
    public function getTheme()
    {
        return $this->theme;
    }
    public function display($part)
    {
        if(!is_file("themes/$this->theme/$part.php"))
        {
            throw new ThemeException("Unable to load theme part: themes/$this->theme/$part.php");
        }
        else
        {
            return 'So far so good';
        }
    }

}

And usage:

error_reporting(E_ALL);

require_once('config.php');
require_once('functions.php');

try
{
    $core = new Core();
}
catch(CoreException $e)
{
    echo 'Core Exception: '.$e->getMessage();
}
echo $core->theme->getTheme();
echo "<br />";
echo $core->language->getLang();

try
{
    $core->theme->display('footer');
}
catch(ThemeException $e)
{
    echo $e->getMessage();
}

I don’t like those exception handlers – i don’t want to catch them like some pokemons… I want to use things simple:
$core->theme->display(‘footer’);
And if something is wrong, and debug mode is enabled, then aplication show error. What should i do?

Answer 1

I’m not familiar with PHP, but you should definately stop doing pokemon exceptions. First, there should be no need to replace every exception (PDOException) with a specific exception (CoreException). Second, use multiple catch blocks in your usage section, like this:

try
{
   $core->theme->display('footer');
}
catch(ThemeException $e)
{
   echo $e->getMessage();
}
catch(PDOException $e)
{
   echo $e->getMessage();
}

Your class “Core” can then shrink down considerably (no more try/catch for each item). Granted, you will show more catch blocks at a higher level, but that is what you should be doing with OOP and exceptions.

Finally, check to see if there already is an exception super-class for some subset of the exceptions you are trying to catch. That will reduce the number of catch blocks.