What is composer? What is composer used for?

If you have ever written anything in PHP before, you have probably found that it feels like you have to keep re-inventing the wheel anytime you want to do a common task such as User Authentication, Database Management or Request Routing. PHP now has a handful of mature frameworks that have already solved all of these problems, so wouldn’t it be easier to cherry pick the bits that you needed from each framework?

If you were to start manually picking the bits you wanted from Zend, or Laravel or Symfony, then it would become very difficult to manage. Each library might also have dependencies, and so you would end up in a mess, particularly if you required other people to work on your project.

This is where Composer comes in. Composer is a dependency manager for PHP. Composer will manage the dependencies you require on a project by project basis. This means that Composer will pull in all the required libraries, dependencies and manage them all in one place.

This kind of management for dependencies in a project is not a new concept, and in fact, much of Composer is actually inspired from npm from Node.js and Bundler from Ruby.

You might also be aware of PEAR. PEAR is an established PHP package manager that has been around for years. PEAR however, has been abandoned by many PHP developers for a number of reasons. Firstly, much of the code in PEAR is out-of-date. Secondly, PEAR forces you to install packages system wide, rather than on a project-by-project basis. This means that if you already have a project that relies on a slightly older package, you are screwed. For an excellent history of PHP packages, read Packages: The Way Forward for PHP by Phil Sturgeon.

How can I install composer?

Installing Composer is really easy as it can all be done through the command line. I’m using OS X, but the following should be the same for any *nix operating system.

So fire up Terminal and run the following commands:

The first command downloads the composer.phar file to your computer. The second line moves the composer.phar file in to your bin so that is accessible globally on your computer.

Now run the following command:

If you have installed Composer successfully, you should be given a list of available commands and descriptions.

What I learn:

Composer is a dependency manager for PHP. Composer can manage the dependencies required by a project by project basis. It is quite useful.