Monolithic Repositories with Composer and Relative Autoloading

Just was reminded on Twitter by Samuel that there is a way for monolithic PHP repositories with multiple components that I haven't mentioned in my previous post.

It relies on a new composer.json for each component and uses the autoloading capabilities of Composer in a hackish way.

Assume we have two components located in components/foo and components/bar, then if bar depends on foo, it could define its components/bar/composer.json file as:

{
    "autoload": {
        "psr-0": {
            "Foo": "../foo/src/"
        }
    }
}

This approach is very simple to start with, however it has some downsides you must take into account:

• you have to redefine dependencies in every composer.json that relies on another component.
• if foo and bar depend on different versions of some third library baz that are not compatible, then composer will not realize this and your code will break at runtime.
• if you want to generate deployable units (tarballs, debs, ..) then you will have a hard time to collect all the implicit dependencies by traversing the autoloader for relative definitions.
• A full checkout has multiple vendor directories with a lot of duplicated code.

I think this approach is ok, if you are only sharing a small number of components that don't define their own dependencies. The Fiddler approach however solves all these problems by forcing to rely on the same dependencies in a project globally and only once.