Five Composer Tips Every PHP Developer Should Know

Composer is the way that that PHP developers manage libraries and their dependencies. Previously, developers mainly stuck to existing frameworks. If you were a Symfony developer, you used Symfony and libraries built around it. You didn’t dare cross the line to Zend Framework. These days however, developers focus less on frameworks, and more on the libraries they need to build the project they are working on. This decoupling of projects from frameworks is largely possible because of Composer and the ecosystem that has built up around it.

Like PHP, Composer is easy to get started in, but complex enough to take time and practice to master. The Composer manual does a great job of getting you up and running quickly, but some of the commands are involved enough so that many developers miss some of their power because they simply don’t understand.

I’ve picked out five commands that every user of Composer should master. In each section I give you a little insight into the command, how it is used, when it is used and why this one is important.

1: Require

$ composer require monolog/monolog

Require is the most common command that most developers will use when using Composer. In addition to the vendor/package, you can also specify a version number to load along with modifiers. For instance, if you want version 1.18.0 of monolog specifically and never want the update command to update this, you would use this command.

$ composer require monolog/monolog:1.18.0

This command will not grab the current version of monolog (currently 1.18.2) but will instead install the specific version 1.18.0.

If you always want the most recent version of monolog greater than 1.8.0 you can use the > modifier as shown in this command.

$ composer require monolog/monolog:>1.18.0

If you want the latest in patch in your current version but don’t want any minor updates that may introduce new features, you can specify that using the tilde.

$ composer require monolog/monolog:~1.18.0

The command above will install the latest version of monolog v1.18. Updates will never update beyond the latest 1.18 version.

If you want to stay current on your major version but never want to go above it you can indicate that with the carrot.

$ composer require monolog/monolog:~1.18.0

The command above will install the latest version of monolog 1. Updates continue to update beyond 1.18, but will never update to version 2.

There are other options and flags for require, you can find the complete documentation of the command here.

2: Install a package globally

The most common use of Composer is to install and manage a library within a given project. There are however, times when you want to install a given library globally so that all of your projects can use it without you having to specifically require it in each project. Composer is up to the challenge with a modifier to the require command we discussed above, global. The most common use of this is when you are using Composer to manage packages like PHPUnit.

$ composer global require "phpunit/phpunit:^5.3.*"

The command above would install PHPUnit globally. It would also allow it to be updated throughout the 5.0.0 version because we specified ~5.3.* as the version number. You should be careful in installing packages globally. As long as you do not need different versions for different projects you are ok. However, should you start a project and want to use PHPUnit 6.0.0 (when it releases) but PHPUnit 6 breaks backwards compatibility with the PHPUnit 5.* version, you would have trouble. Either you would have to stay with PHPUnit 5 for your new project, or you would have to test all your projects to make sure that your Unit Tests work after upgrading to PHPUnit 6.

Globally installed projects are something to be thought through carefully. When in doubt, install the project locally.

3: Update a single library with Composer

One of the great powers of Composer is that developers can now easily keep their dependencies up-to-date. Not only that, as we discussed in tip #1, each developer can define exactly what “up-to-date” means for them. With this simple command, Composer will check all of your dependencies in a project and download/install the latest applicable versions.

$ composer update

What about those times when you know that a new version of a specific package has released and you want it, but nothing else updated. Composer has you covered here too.

$ composer update monolog/monolog

This command will ignore everything else, and only update the monolog package and it’s dependencies.

It’s great that you can update everything, but there are times when you know that updating one or more of your packages is going to break things in a way that you aren’t ready to deal with. Composer allows you the freedom to cherry-pick the packages that you want to update, and leave the rest for a later time.

4: Don’t install dev dependencies

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