Question

I have 3 class name “Controller“,”Loader“,”Error” and “Ex_controller“.

“Controller.php“

class Controller
{
     function __Construct()
     {
           $this->load = Loader::getinstant();
           $this->error = $this->load->class('Error');
     }
}

“Loader.php“

class Loader
{
     function class($class)
     {
           require_once($class);
           return new $class;
     }
}

“Error.php“

class Error
{
     function query($query)
     {
           $res = mysql_query($query)
           if($res)
           {
                  return $res;
           }else{
                  die('Could not execute query: '.mysql_error().'at line '. __LINE__ . 
                       ' in file ' . __FILE__);//does it work?If it doesn't, how to
                                                 make it work?
           }
     }
}

“Ex_controller.php“

class Ex_controller extends Controller
{
     function __Construct()
     {
           parent::__construct();
           $result = $this->error->query('some sql query');//(*)
     }
}

How can I show where the error occur in Ex_controller with (*)?

Answer 1

First of all, you should stop using mysql_xxx functions as they’re in the process of deprecating the old API.

That aside, in this case, it’s probably worthwhile to start using exceptions instead of a plain old die().

if($res) {
    return $res;
}else{
    throw new Exception("Could not execute query '$query': " . mysql_error());
}

Then inside the controller:

try {
    $result = $this->error->query('some sql query');//(*)
} catch (Exception $e) {
    die(print_r($e, true)); // do something more useful with the exception though.
}

When you catch the exception higher up and you would print_r() it, you will see the complete stack trace with files, line numbers and everything.

Plus, you get the chance to handle the error as well.

Plus plus, if you would use PDO with exception error handling enabled, you don’t even have to throw exceptions yourself anymore.