Debugging or Troubleshooting the PHP Autoloader

I used PHP pretty heavily a while ago. It’s still – in its primitive, non-objectey, non-frameworked form – one of the environments in which I can ‘think’ in the language the fastest. If someone had a gun to my head and said “build me this thing ‘x'” – I would probably do it in PHP (unless it were large enough with lots of forms/fields/tables/etc., then I might use something else. Or maybe still PHP? I dunno.)

But that means I missed out on the newest revolutions in PHP – composer, Laravel, all that stuff. And some of it is actually pretty cool, once you get a handle on it.

Composer is very similar to how Bundler works under Ruby, or how npm works under Node. You say which libraries you need and which versions in a config file, then say ‘composer install’ (or ‘php composer.phar install’) and it magically goes and gets them and installs them. Pretty neat.

One of the more subtle pieces you get is no longer having to say require "foo.php"; – the new system of Autoloading does that for you, if you’ve gotten everything set up right. It seems to be powered by PHP Namespaces – each composer-able package declares which namespace it’s going to set stuff up in, and then if you try and use something from that namespace, it automagically gets loaded up. Pretty neat!

It’s actually very neat. Until…it doesn’t work. And then I started to find that it was extremely difficult to troubleshoot what it’s actually doing, and why my custom package wouldn’t autoload.

Probably the first place to start should be the DebugClassLoader component ("/Symfony/Component/Debug/DebugClassLoader.php"). That was installed by default in the Laravel app I was playing with. It looks like there’s a nice static class method you can invoke, which will help troubleshoot what’s going on in the class-loading process – “DebugClassLoader::enable()“. There seemed to be another Debug component – somewhere – that wanted to enable that feature – “/Symfony/Component/Debug/Debug.php” – but I couldn’t end up figuring out how to turn the damned thing on. If you do? I bet that’ll be more helpful than the other stuff I ended up playing around with. That DebugClassLoader seems like it will wrap the autoloading process and yell at you if it can’t find the classes it wants in the appropriate files, and there’s not a lot else going on with the autoload sequence than that.

But, due to my ignorance, the most useful tool that worked for me was manually loading up the autoloader object and just asking it dumb questions:

$autoloader = require "./vendor/autoload.php";

$results = $autoloader->findFile("\MyNamespace\MyClassName");

print "Found file for class at: $results";
exit(1);

Other methods I ended up playing with were:

$autoloader->loadClass("\MyNamespace\MyClassName");

print_r($autoloader);
exit(2);

Enough poking around with some of these techniques eventually got me to the point where I could figure out what it was that I was doing wrong. Hopefully I can save someone else a few hours of heartache too.