Warning: this post is old and might not reflect the current state of the art

Composer has proven to be the best modern dependency management solution for PHP.

Composer filled a need and now is on the same level as what npm is for Node.js packages.

Combined with Packagist, the official repository for Composer packages, it’s a utility you cannot avoid using.

## Installing Composer on OSX / Linux

curl -sS https://getcomposer.org/installer | php

and

mv composer.phar /usr/local/bin/composer

More details on installation

## Using Composer

Initialize Composer by typing

composer init

in the root of the project. Follow the instructions, you’ll end up with a composer.json file. This is the file that contains all the project dependencies.

Now type

composer install

This command will download all the dependencies in the vendor folder and create a composer.lock file.

The vendor folder contains the packages folders, plus an autoload.php file and the composer folder, which are internal Composer files.

To include the dependencies include vendor/autoload.php in your PHP main file:

require 'vendor/autoload.php'

and all will just work.

To add more dependencies to the project type

composer require packagename:1.0

Example:

composer require filp/whoops:2.0

## Updating dependencies

Run

composer update

Composer will search for updates for the packages you specified, taking into consideration any versions limit you added, and will update the composer.lock file.

## Package versions

Most used version formats:

• “1.0”: will install that precise version
• “~1.0”: will install any update to 1.0, 1.0.1, 1.0.20 but will not install version 1.1 and later versions.

## composer.lock

Whenever you update the installed dependencies running composer install or composer update, the composer.lock file will be updated to reflect it. So if you add this file to the repository everyone that downloads the project and runs composer install will get the exact same versions you installed, even if a newer one satisfying the version limits in composer.json is available.

They need to run composer update to get the latest releases available.

Add your project’s composer.json and composer.lock to VersionEye to be notified via email when your dependencies are updated, so you can update them in your project.
Add your composer.lock to Security Advisories Checker