A short intro to Composer

If you’re familiar with the WordPress plugin world, but haven’t used Composer before, this introduction is for you.

Composer is the industry standard for managing community-built PHP packages. Much like NPM for JavaScript.

With Composer, you don’t have to download, extract and move a library or piece of functionality into your project, but you can install it with a simple command that you run in your terminal.

To install Timber, you would use composer require.

composer require timber/timber

Before you can run this command, you need to have Composer installed. Follow the official guide for the installation.

In addition to that, you probably want to be able to use the composer command in your terminal.

# Install Composer as a global command.
mv composer.phar /usr/local/bin/composer

Now, after you’ve installed Composer, where would you run the composer require timber/timber command? It depends. But generally, you would run it from your project’s root folder.

When you run that command, Composer will do a couple of things.

composer.json #

Composer will create composer.json file if there isn’t already one in your project. In that file, it will make a new entry for the installed package:

{
  require: {
    "timber/timber": "^2.0.0"
  }
}

The vendor folder #

Composer will create a vendor folder in your project and download the Timber package as well as other packages that Timber relies on into that folder.

It will also create a vendor/autoload.php file, which is the entry point to all your packages. Here’s where Composer really shines.

Autoloading #

Maybe you’re used to require all the files you need separately?

require_once 'functionality-a.php';
require_once 'class-b.php';
require_once 'class-c.php';

With Composer, the only thing you need to do to make all functionality available is the following.

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

Usually, you would do that at the top of your functions.php file of your WordPress theme.

After that, you can initialize and use all Timber classes, they will be autoloaded as soon as they’re needed.