You know the saying: if debugging means taking the bugs out, then programming means putting them in. Yes. We all have bugs in our code. And since not all of them can be marketed as “undocumented features”, from time to time we have to debug our applications.

The best debugger for PHP I’ve used so far is Zend’s. Zend Platform together with Zend Studio constitutes a very good development environment and a great debugging environment. Due to the fact that Zend Studio is a little pricey, I don’t use it any more, instead I’m using a highly customised vim. This makes a great development environment, but unfortunately isn’t not that great when debugging. I know you can use vim with Xdebug, but it’s quite a chore, and I don’t like it. Since old school debugging with var_dump() or print_r() is out of the question, I was looking for another way to debug my applications. And I’ve found just the thing: FirePHP. It’s a Firefox extension, just like FireBug – that can receive debug information from the server.

Since I do most of my bugging programming on Zend Framework, I also need debugging for this platform. I use the OOP based bootstraping method, where you extend your Bootstrap class from Zend_Application_Bootstrap_Bootstrap. And in the .htaccess file of the /public/ directory, I have an envelope with the current state of application (usually on of development/staging/production):

SetEnv APPLICATION_ENV development

Normally, I need the debug information only when the application is in the “development” state, so I’m using this method in the Bootstrap class.

class Bootstrap extends Zend_Application_Bootstrap_Bootstrap {
    // Bootstrap other components

    /**
     * inits FirePHP for debugging
     *
     * @return void
     */
    protected function _initFirebugDebugger() {
        if(APPLICATION_ENV == 'development') {
            // don't debug while not in "development"
            $logger = new Zend_Log();
            $writer = new Zend_Log_Writer_Firebug();
            $logger->addWriter($writer);

            Zend_Registry::set('logger',$logger);
        }
    }
}

I also like to have some syntactic sugar when developing, so I’ve define this function in the Bootstrap.php file. Yes, I know that this might be perceived as a blasphemy by some of the OOP purists out there, but I really don’t care. If you don’t want non-OOP “stains” on your code, simply create a YourApplication_Utility_Firebug class or whatever with a static debug() method and paste the code in it.

/**
 * syntactic sugar for logging errors
 * and debug messages to FireBug
 *
 * @param string $message
 * @param int $label
 * @return void
 */
function fb($message, $label = null) {
    if($label != null) {
    	$message = array($label, $message);
    }

    if(Zend_Registry::isRegistered('logger')) {
    	Zend_Registry::get('logger')->log($message);
    }
}

And now, any time you need to debug something, simply type:

fb($variable);
fb($_POST); // and so on

And all these variables will be sent to Firefox’s FirePHP toolbar and you can inspect them from there. For even better results, you can also send debug information from your ErrorController to FirePHP (comes in handy when using Ajax).

PS: I’ll have a look into FireLogger for PHP. It also look pretty interesting, although it’s only in Beta.