Quick ‘n’ Dirty PHP/Drupal REPL

In my new job at [WANdisco] 1 I’ve been stuck trying to understand Drupal for a few weeks (which you may have gathered from my Identi.ca feed!).

I’ve got Xdebug and Emacs integrated quite nicely via GEBEN, which is pretty cool, but running everything through a debugger can be frustrating at times. Sometimes I just want to evaluate an expression, without loading a browser page, without new Emacs windows appearing, etc. It’s sometimes tempting to use print_f debugging, but I know that it will come back to bite me if I do.

Instead, I’ve thrown together the following read-eval-print-loop (REPL) for Drupal. Run it using drush php-script repl.php, preferably as your Web-server user (www-data in my case). It took approximately 30 seconds to write, so don’t expect it to handle edge cases gracefully!

<?php

// VERY simple read-eval-print-loop (REPL) for PHP.
// Useful for running with "drush php-script repl.php"
echo "\\nphp> ";
while (($line = fgets(STDIN)) !== FALSE) {
    try {
        var_dump(eval($line));
    } catch (Exception $e) {
        echo "\\nUncaught Exception: " . var_export($e, TRUE);
    }
    echo "\\nphp> ";
}

Run it and you’ll get a command-line php>, where you can run lines of PHP. Note that you need to put complete lines, ie. you need to include the semicolon, and code which normally straddles several lines (eg. if, for, while, etc.) may need to be squashed on to one.

Use of echo, var_dump, etc. is the same as any other commandline PHP. I’ve wrapped return values in var_dump as a shortcut, since I normally var_dump everything I’m looking at (eg. echo FALSE; gives an empty string, var_dump(FALSE); gives the much more useful (bool) false).

I’ll probably add to this over time, so I may stick it in my Wiki :)

Hope it helps someone!