Composer Version Alias Hack

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With the release of Symfony 4 last month, we’ve slowly been seeing package maintainers update their packages to support the latest version of Symfony components. If you are a package maintainer and haven’t done so, you should check out my guide for supporting multiple versions of Symfony.

What happens if a package you use doesn’t support Symfony 4? You can always fork the repo, add the version constraints and open up a pull request. Often, maintainers are happy to accept your pull request and create a new tag for it in a couple days.

What about a package that isn’t active and could take months for them to update? You could fork it and use your fork in your project, but I’m not a fan of doing this. You could end up with a lot of forks that become stale.

With flex not requiring all of Symfony, you might be able to get away with having a few packages being 3.4. The only difference between 4.0 and 3.4 is removed deprecations.

What if it’s a common package like YAML or Console? What if it’s another common package that has a lot of different version requirements like php-parser? I ran into this last week and it didn’t look like the packages I was wanting to use were going to get updated anytime soon.

Enter the Composer Version Alias hack. This hack allows you to require a version of a package as if it were another. Example:

{
    "require": {
        "symfony/yaml": "4.0.2 as 3.4.0"
    }
}

This is saying that our version 4.0.2 will be imported as 3.4.0. Now any package that requires Symfony YAML version 3, will work because we are aliasing our installed version to 3.4.0.

This hack isn’t ideal. It may not work 100% of the time and can cause upgrading to be annoying (because it requires the full version). If you find yourself needing a package really quick, it can be a lifesaver.

Matt Loberg

Matt Loberg

Principal Software Engineer specializing in Open Source technologies and DevOps.