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FAQ update

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Mike Thompson 2017-08-01 11:22:15 +10:00
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docs/FAQs/UseASubscriptionInAnEventHandler.md
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@ -13,16 +13,16 @@ You should NOT do this:
....))) ....)))
``` ```
If you do: because that `subscribe`:
1. You might create a memory leak (the subscription might not be "freed") 1. might create a memory leak (the subscription might not be "freed")
2. You have just made you event handler impure (it reaches out and grabs a global value). 2. makes the event handler impure (it grabs a global value)
### The Better Way ### The Better Way
Instead, to make the value of a subscription available within an event handler, it has to Instead, the value of a subscription should
be injected into the `coeffects` of that handler via an interceptor. be injected into the `coeffects` of that handler via an interceptor.
The overall sketch is: A sketch:
```clj ```clj
(re-frame.core/reg-event-fx ;; handler must access coeffects, so use -fx (re-frame.core/reg-event-fx ;; handler must access coeffects, so use -fx
:event-id :event-id
@ -32,11 +32,17 @@ The overall sketch is:
....))) ....)))
``` ```
Notes:
1. `inject-sub` is an interceptor which will get the subscription value and add it to coeffects (somehow)
2. The event handler obtains the value from coeffects
So how to write this interceptor?
### Solutions ### Solutions
re-frame doesn't yet have a built in interceptor to do this injection. re-frame doesn't yet have a builtin `inject-sub` interceptor to do this injection.
So you'll need to create your own or you may want to use this 3rd party library: I'd suggest you use this 3rd party library:
https://github.com/vimsical/re-frame-utils/blob/master/src/vimsical/re_frame/cofx/inject.cljc https://github.com/vimsical/re-frame-utils/blob/master/src/vimsical/re_frame/cofx/inject.cljc