Composer Autoloading

Composer Autoloading Not Just for Vendor Files

Teacher can and should learn from students! That is one of the things I find very satisfying about being an adjunct professor at Weber State University. The fact that I can learn new and usual things from those I teach. Last night was one of those times.

In fielding questions about a PHP project a comment came up about multiple autoloaders. In the first project I had the students create their own autoloader. This project I required them to use composer to manage and load dependencies. One student mentioned he had found how to use the composer autoloader to load his classes. Now I had known in the past that composer supported PSR-0 but didn’t fully understand it. So to my surprise I learned that composer now supports PSR-4 and is very easy to use. Here is a code snippet of the a portion of the composer.json file:

"autoload": {
	"psr-4": {
		"Common\\": "src/Common/",
        "Domain\\": "src/Domain/"
   }
}

Then to use the autoloader and namespaces in code you would use a PHP statement like this:

require_once __DIR__.'/vendor/autoload.php';

To optimized the autoloader you can use this command: composer dumpautoload -o. There is a downside to this, though. You will need to re-run this every time a new class is added, in addition to whenever the composer install or update commands are used. Needless to say this is a small price to pay for roughly a 40% performance increase.

This is another great usage of composer. A tool PHP developers should be using a lot more.

• Composer JSON Schema
• PHP Composer Autoloading
• Optimizing Composer’s autoloader performance