Glad I could help. On Monday, 16 March 2015 08:02:40 UTC, Torsten Uhlmann wrote: > > 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> 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 >> > 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 >> > 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. >> > For more options, visit https://groups.google.com/d/optout. >> >
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