CC Container

Metadata & Tags ​

Some collections are painful to maintain by hand: every controller that declares a route, every console command, every event listener. Listing them all in one central place means editing that list each time you add one — and forgetting to is an easy mistake.

Metadata turns that around. You attach arbitrary tags to a service right where it's defined, then ask the container at runtime for every service carrying a given tag. The list assembles itself.

A metadata entry is prefixed with a = character:

ctn
@controller.auth.sign_in: Controller\Auth\SignInController(@auth)
  = route: {'GET', 'POST'}, '/signin'

Multiple entries per key ​

The metadata key is always a vector / array, so you can add multiple entries of the same type:

ctn
@controller.auth.sign_in: Controller\Auth\SignInController(@auth)
  = route: {'GET', 'POST'}, '/signin'
  = tag: 'users'
  = tag: 'auth'

Named sub-keys ​

The elements inside a metadata definition can have named keys:

ctn
@app.bootstrap: Bootstrap()
  = on: 'app.start' call: 'onAppStart'

Looking up tagged services ​

At runtime the container can return all services carrying a given metadata key, which is how you collect, for example, every controller that declared a route. See Looking up services by metadata for the runtime lookup API.