Get access to silex $app in custom Exception constructor?

Question

I would like to use set of custom Exception classes in my project based on silex (silex.sensiolabs.org) framework. I prefer to write an error message into log file in function "__construct". Is there a way to access to $app['monolog'] inside __construct function of MyException class? I think what to use an $app as constructor parameter or as global variable is not elegant way.

class MyException extends Exception
{
    public function __construct($message = '')
    {
        parent::__construct($message);
        //how to do?
        $app['monolog']->addError($message);
    }
}

Answer 1

If you really wanted to, you could have your Exceptions created by the service container (Pimple):

class MyException extends Exception
{
    public function __construct($message = '', $monolog)
    {
        parent::__construct($message);
        $monolog->addError($message);
    }
}

// no share() => create new instance every time
$app['my_exception'] = function ($app) {
    return new MyException($app['monolog']);
};

It'd strongly advise against this, you don't want to couple your exceptions to logging logic. A way better approach would be to add an error handler that logs it.

Example:

$app->get('/error', function () {
    throw new MyException('A totally expected error happened.');
});

$app->error(function ($e) use ($app) {
    if ($e instanceof MyException) {
        $app['monolog']->addError($message);
    }
});

If an error handler does not return anything, the other error handlers will be called until one returns.

Note: In case you didn't know, the monolog service provider already logs all exceptions.