Interesting; I had started playing with the core.async approach, and
it's good to see that Pedestal's on that same path.
Brian, I like that too. It looks like you're providing the state when
you do the def-action? Is the "self" variable "state", captured through
the closure?
Walter van der Laan wrote:
An alternative that I'm looking at is pedestal 0.3.0. It sort of works
like this...
;; Create a transform-channel and transform-function to handle all
changes to 'state'
(defn init []
(let [c (chan)]
(go (while true
(when-let [[path v] (<! c)]
(swap! state assoc-in path v))))
c))
(def transform-chan (init))
(defn transform [path v]
(>! transform-chan [path v]))
;; Change the state by calling transform
(transform [athlete-number :active?] true)
(transform [athlete-number :timestamp] ms)
;; Create an inform-channel where functions can subscribe to changes
in 'state'
(def inform-channel-subscriptions
[[update-timestamp [:* :timestamp]]
[update-active [:* :active?]]])
This approach is described in:
https://github.com/pedestal/pedestal/blob/master/app/examples/walkthrough.clj
On Friday, November 29, 2013 6:58:32 PM UTC+1, Sam Ritchie wrote:
Hey guys,
As I start to work on more Clojurescript UI code, I've been
running into a pattern with atoms and watches that I THINK I can
abstract away... but the solution feels wrong, and I'd love to
hear a better way.
Say I'm building a stopwatch for timing runners in a race. I've
got a clojure record like this:
(defrecord StopwatchState [
active? ;; timer running?
timestamp ;; UTC time of this particular state
stopwatch-time ;; the time on the stopwatch as of "timestamp"
results ;; pairs of [athlete number, time]])
and a bunch of functions that toggle the timer, mark an athlete
crossing the line, update the timer, etc.
My view holds the current state in an atom:
(def state (atom ,,some-stopwatch-state))
and I update my views by adding watches to the atom and refreshing
the various UI components to match the new state.
Now! Here's the annoying pattern. In the cljs UI world, to poke
these atoms, I end up wrapping all of my model functions like this:
(defn toggle! []
(swap! state toggle))
(defn mark! [athlete-number]
(swap! state mark athlete-number))
I can think of two ways to break the pattern.
1) A deep-code-walking macro that transforms code like (mark state
athlete-number) into (swap! state mark athlete-number) if the
first argument is an atom;
2) a defstatefn macro that defines the "mark" and "mark!" versions
at the same time.
Both feel wrong. My goal is to program in a more declarative way.
Is there a better way to structure UI code?
--
Sam Ritchie (@sritchie)
Paddleguru Co-Founder
703.863.8561
www.paddleguru.com <http://www.paddleguru.com/>
Twitter <http://twitter.com/paddleguru>// Facebook
<http://facebook.com/paddleguru>
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Sam Ritchie (@sritchie)
Paddleguru Co-Founder
703.863.8561
www.paddleguru.com <http://www.paddleguru.com/>
Twitter <http://twitter.com/paddleguru>// Facebook
<http://facebook.com/paddleguru>
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