codebright

The Primers 19
You can add as many dependencies as you like to your project. Go ahead, add a billion! Prove me
wrong.
Listen, do you want to know a secret? Do you promise not to tell? Woah, oh oh. Closer, let me
whisper in your ear. Say the words you long to hear…
Your dependencies can have their own dependencies.
That’s right! Your dependencies are also Composer packages. They have their own composer.json
files. This means that they have their own require section with a list of dependencies, and those
dependencies might even have more dependencies.
Even better news, is that Composer will manage and install these nested dependencies for you. How
fantastic is that? Wolverine might need tools/claws, tools/yellow-mask, and power/regeneration
but you don’t have to worry about that. As long as you require the xmen/wolverine package then
Composer will take care of the rest.
As for dependency versions, they can assume a number of different forms. For example, you might
not care about minor updates to a component. In which case, you could use a wildcard within the
version, like this:
1 "xmen/gambit": "1.0.*"
Now Composer will install the latest version that starts with 1.0. For example, if Gambit had versions
1.0.0 and 1.0.1, then 1.0.1 would be installed.
Your package might also have a minimum or maximum boundary for package versions. This can be
defined using the greater-than and less-than operators.
1 "xmen/gambit": ">1.0.0"
The above example would be satisfied by any versions of the xmen/gambit package that have a
greater version number than 1.0.0.
1 "xmen/gambit": "1.0.0"
2 "xmen/gambit": "=