Stop called twice on composed system about component HOT 2 CLOSED

I've slightly refactored my approach to this:

(component/system-map
  :a (new-a)
  :app
    (component/using
      (component/system-map
        :b (new-b)
        [:a])))

I prefer this (though it may be incorrect) because :a is directly accessible by :b (instead of having to get-in) and also because I can strictly control what bits of the core system are actually exposed to the app (as you can guess, there are more stuff than just :a in the core system).

In any case, I still see :a being stopped twice on shutdown...

from component.

Nested systems don't really work. It's easier to compose systems as one flat map with namespaced keys.

See discussion at https://groups.google.com/d/msg/clojure/2-baBp61XTs/ajRgkVZNKjEJ for why lifecycle functions happen twice.

from component.