Exception exceptions

Question

I am trying to create a site using OOP in PHP. Everyone is talking about Singleton, hermetization, MVC and using exceptions. So I tried to do it like this:

Class for building the 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 Management 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 use:

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 do not like these exception handlers - I do not want to catch them, like some Pokémon ... I want to use things simply: $ Core-> theme-> display ('footnote'); And if something is wrong, and debugging mode is enabled, then an application error appears. What should I do?

Answer 1

PHP, pokemon. -, (PDOException) (CoreException). -, catch , :

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

"Core" ( try/catch ). , catch , , .

, , , . catch.

Answer 2

, ( - script ).

-

if (debug_is_on())
    throw new MyException(...);

, error_reporting.

Answer 3

. , , Front Controller, .

, :

<?php
class ErrorHandler
{
    // Private constructor to prevent direct creation of object
    private function __construct()
    {
    }

    /* Set user error-handler method to ErrorHandler::Handler method */
    public static function SetHandler($errTypes = ERROR_TYPES)
    {
        return set_error_handler(array ('ErrorHandler', 'Handler'), $errTypes);
    }

    // Error handler method
    public static function Handler($errNo, $errStr, $errFile, $errLine)
    {

        $backtrace = ErrorHandler::GetBacktrace(2);

        $error_message = "\nERRNO: $errNo\nTEXT: $errStr" .
                     "\nLOCATION: $errFile, line " .
                     "$errLine, at " . date('F j, Y, g:i a') .
                     "\nShowing backtrace:\n$backtrace\n\n";

        // Email the error details, in case SEND_ERROR_MAIL is true
        if (SEND_ERROR_MAIL == true)
        error_log($error_message, 1, ADMIN_ERROR_MAIL, "From: " .
        SENDMAIL_FROM . "\r\nTo: " . ADMIN_ERROR_MAIL);

        // Log the error, in case LOG_ERRORS is true
        if (LOG_ERRORS == true)
        error_log($error_message, 3, LOG_ERRORS_FILE);

        /* Warnings don't abort execution if IS_WARNING_FATAL is false
         E_NOTICE and E_USER_NOTICE errors don't abort execution */
        if (($errNo == E_WARNING && IS_WARNING_FATAL == false) ||
        ($errNo == E_NOTICE || $errNo == E_USER_NOTICE))
        // If the error is nonfatal ...
        {
            // Show message only if DEBUGGING is true
            if (DEBUGGING == true)
            echo '<div class="error_box"><pre>' . $error_message . '</pre></div>';
        }
        else
        // If error is fatal ...
        {
            // Show error message
            if (DEBUGGING == true)
            echo '<div class="error_box"><pre>'. $error_message . '</pre></div>';
            else
            echo SITE_GENERIC_ERROR_MESSAGE;

            // Stop processing the request
            exit();
        }
    }

    // Builds backtrace message
    public static function GetBacktrace($irrelevantFirstEntries)
    {
        $s = '';
        $MAXSTRLEN = 64;
        $trace_array = debug_backtrace();

        for ($i = 0; $i < $irrelevantFirstEntries; $i++)
        array_shift($trace_array);
        $tabs = sizeof($trace_array) - 1;

        foreach ($trace_array as $arr)
        {
            $tabs -= 1;
            if (isset ($arr['class']))
            $s .= $arr['class'] . '.';
            $args = array ();

            if (!empty ($arr['args']))
            foreach ($arr['args']as $v)
            {
                if (is_null($v))
                $args[] = 'null';
                elseif (is_array($v))
                $args[] = 'Array[' . sizeof($v) . ']';
                elseif (is_object($v))
                $args[] = 'Object: ' . get_class($v);
                elseif (is_bool($v))
                $args[] = $v ? 'true' : 'false';
                else
                {
                    $v = (string)@$v;
                    $str = htmlspecialchars(substr($v, 0, $MAXSTRLEN));
                    if (strlen($v) > $MAXSTRLEN)
                    $str .= '...';
                    $args[] = '"' . $str . '"';
                }
            }

            $s .= $arr['function'] . '(' . implode(', ', $args) . ')';
            $line = (isset ($arr['line']) ? $arr['line']: 'unknown');
            $file = (isset ($arr['file']) ? $arr['file']: 'unknown');
            $s .= sprintf(' # line %4d, file: %s', $line, $file);
            $s .= "\n";
        }

        return $s;
    }
}
?>

, .

//determines if the application will fail on E_WARNING level errors.
define('IS_WARNING_FATAL', true);
//determines error message shown
define('DEBUGGING', true);
// The error types to be reported
define('ERROR_TYPES', E_ALL);

// Settings about mailing the error messages to admin
define('SEND_ERROR_MAIL', false);
define('ADMIN_ERROR_MAIL', '[e-mail]');
define('SENDMAIL_FROM', '[e-mail]');


//Saves errors to a file when true
define('LOG_ERRORS', false);
define('LOG_ERRORS_FILE', 'path-to-error-log');
/* Generic error message to be displayed instead of debug info
 (when DEBUGGING is false) */
define('SITE_GENERIC_ERROR_MESSAGE', '<h1>An unknown error occurred!  Our webmaster has been notified.</h1>');