Something like this:
(defn component [data owner]
(reify
om/IInitState
(init-state [_]
(let [chan (chan)]
{:chan chan
:kill (chan)
:pub (pub chan first)}))
om/IWillMount
(will-mount [_]
(let [pub (om/get-state owner :pub)
chan (chan)
kill (om/get-state owner :kill)]
; If using pub/sub, need to subscribe
*(sub pub :foo chan) *
(go-loop []
(let [*[v c]* *(alts! [chan kill])*]
(when-not *(= c kill)*
(do-something v)
(recur))
; If using pub/sub, need to unsubscribe:
*(unsub pub :foo chan)*))))
om/IWillUnmount
(will-unmount [_]
*(put! (om/get-state owner :kill) :quit)*)
om/IRenderState
(render-state [_ {:keys [chan]}]
(dom/div {:onClick #(put! chan [:foo "Hello"])}
"Click me to send [:foo \"Hello\"]"))))
On 30 August 2014 16:08, Dhruv Bhatia <[email protected]> wrote:
> On Sunday, 13 July 2014 01:46:41 UTC+10, Daniel Kersten wrote:
> > Channels are cheap, but unless they get garbage collected (and I assume
> not closing them will prevent this), they will still take up some resources.
> >
> >
> > Related and important is that you shut down any go blocks that you
> create in IWillMount, especially if they take from a channel which may
> still be receiving data (eg: through mux or pub/sub). If you don't shut
> these down, they will continue to run even after the component has
> unmounted and if the component is later mounted again, you will have
> multiple go blocks doing the same thing! Besides using resources, this can
> actually be dangerous if you are accessing owner inside the go block (eg to
> set local state) as you may end up accessing an unmounted owner. The
> simplest solution is having a kill channel that you listen on using
> async/alt that gets closed in the IWillUnmount and that terminates the go
> block.
>
> Thanks for the explanation. Would you be able to provide a code example
> that demonstrates how to properly clean up a pub/sub watcher within a
> component's IWillUnmount lifecycle method?
>
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