Detailed Backtracing for Error Reporting in PHP

It can be useful to have detailed error messages when you are trying to debug code. This can be used to display detailed messages to the screen when in your development environment.

Here's the code

<?php
// Define a custom error handler for more details
function detailed_err($errno, $errstr, $errfile, $errline, $errcontext) {
    // First of all, begin by noting that a fatal error occurred, and basic
    // details just like a normal error report:
    echo "<p>FATAL ERROR - {$errstr}</p>\n";

    // Now use debug_print_backtrace to give the function call list in
    // a compressed format easy for quick scanning:
    echo "<pre>\nFunction Call Tree:\n";
    debug_print_backtrace();

    // To finish off our 'extreme' debugging mode here, let's also give
    // a full backtrace dump, which will contain all variables that existed
    // and much much more.
    echo "\nFull Backtrace:\n";
    var_dump(debug_backtrace());

    // Close off that pre tag
    echo "</pre>\n";

    // That's it, time to make sure the script dies:
    die();
}

// Now go ahead and register this as the error handler:
set_error_handler('detailed_err', E_ERROR | E_USER_ERROR);
?>

This example makes full use of debug_bracktrace(), which gives you a full list (as an array) of all currently open function calls, variables, line numbers, and more. It also uses debug_print_backtrace(), which gives a smaller, simpler output to the backtrace to make it easier to just see the heart of the problem. Combined, this makes for as much detail as you could really care to have.

Of course, you would certainly want to make sure that this is enabled only on your development environment. You would not want this level of detail about your system to be displayed to the end user. However, you could modify this on your production server so that instead of outputting all this to the screen, it could send it as an email to you instead. That way if a fatal error happens on the website, you will be instantly notified and have all the information possible to go and debug it.

Hop it helps.