Hi Colin, the thing I was missing is the entry point into the system, or a way to get hold of my current component. After re-watching the talk and looking at the slides (http://stuartsierra.com/download/2014-06-27-components-euroclojure.pdf) I found him mentioning these on slides #94 to #105. So the ways he describes to be able to pass a dependency as an argument to an API function of that dependency are:
- putting the system into a var or atom - adding a middleware to add the system or part of it to the request - create the routes in scope of the start function so you're able to pass the component and dependencies around. These are the examples he mentioned, I'm sure there are other ways. But it helped me to break out of that brain lock state of mine. Thanks for your extended help, Torsten. Am Sonntag, 15. März 2015 19:15:04 UTC+1 schrieb Colin Yates: > > If you haven't already then you might want to watch: > https://www.youtube.com/watch?v=13cmHf_kt-Q > > If it helps: > > (defn a-real-worker [db] > ...) > > (defrecord ARealWorkerComponent [db registry] > components/Lifecycle > (start [this] > (registry-api/register registry (partial a-real-worker-fn db)) > this) > (stop [this] > ....))) > (defn a-real-worker-component [] > (map->ARealWorkerComponent {})) > > ;; in the layer above these components > (def system (components/systemmap > :db (infrastructure/new-db) > :a-real-worker (components/using > (a-real-worker-api/a-real-worker-component) > [:db])) ;; THIS IS WHERE IT GETS WIRED UP > > So the real work is done in a-real-worker but it needs collaborators. > It does that with ARealWorkerComponent (which probably also registers > (a-real-worker...) with a registry of some sort. > > When you call start the library will parse the 'using' meta-data to > provide the dependencies the component needs. > > Your question of how to actually *call* a-real-worker depends on your > dispatching. Check out https://github.com/danielsz/system for some > examples of using ring handlers for example. > > HTH > > > On 15 March 2015 at 17:30, Torsten Uhlmann <torsten...@gmail.com > <javascript:>> wrote: > > Colin, > > > > thanks for the thoughtful explanation! > > > > I still have a problem understanding the flow. Say I want to call a > > component function (like "get-user") from another component that depends > on > > the database component. > > > > I still don't understand how a component function accesses it's > > dependencies? There is the Lifecycle record that gets passed the > > dependencies, constructs the component and returns a new map in the > start or > > stop function. But any function of that component is not defined inside > the > > scope of defrecord (correct ?) and the component map. So how would that > > function access its own dependencies. > > > > I have the feeling that this problem comes from some very basic > > misunderstanding on my end. Something very basic I'm missing. > > > > Thanks, > > Torsten. > > > > -- > > You received this message because you are subscribed to the Google > > Groups "Clojure" group. > > To post to this group, send email to clo...@googlegroups.com > <javascript:> > > Note that posts from new members are moderated - please be patient with > your > > first post. > > To unsubscribe from this group, send email to > > clojure+u...@googlegroups.com <javascript:> > > For more options, visit this group at > > http://groups.google.com/group/clojure?hl=en > > --- > > You received this message because you are subscribed to the Google > Groups > > "Clojure" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to clojure+u...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
