When I try this using your code above I get a stack-trace that I can't
understand. Am I using it wrong?
(transparent-chan c)
> (transparent-put c 42)
> (transparent-take c)
-
>
> "Exception in thread \"async-dispatch-64\" "
> "java.lang.IllegalArgumentException: No implementation of method:
> :take! of protocol: #'clojure.core.async.impl.protocols/ReadPort found for
> class: nil"
> "\tat clojure.core$_cache_protocol_fn.invoke(core_deftype.clj:541)"
On Monday, May 12, 2014 1:16:19 PM UTC+9, James Reeves wrote:
>
> On 12 May 2014 03:41, gamma235 <jesus.d...@gmail.com <javascript:>> wrote:
>
>>
>> (defn log-name [ch] (symbol (str ch '-log)))
>>>
>>> ;; Is this efficiently written?
>>> (defmacro transparent-chan [ch]
>>> (do
>>> `(def ~ch (chan))
>>> `(def (log-name ~ch) (atom []))
>>> `(println "new transparent channel created!")))
>>>
>>
> This looks like you're replicating the functionality of maps using defs.
> Instead, consider something like:
>
> (defn transparent-chan [ch]
> {:channel ch, :buffer (atom [])})
>
> Another improvement you may wish to consider is to use a queue, rather
> than a vector. Immutable queues exist in Clojure, but are something of a
> hidden feature.
>
> (defn transparent-chan [ch]
> {:channel ch, :buffer (atom clojure.lang.PersistentQueue/EMPTY)})
>
> Queues act more like channels, in that popping a queue strips off the
> oldest item, whereas popping a vector strips off the newest.
>
> With this in mind, you could write functions like:
>
> (defn transparent-put [{:keys [channel buffer]} x]
> (go
> (>! channel x)
> (swap! buffer conj x)))
>
> (defn transparent-take [{:keys [channel buffer]} x]
> (go
> (let [x (<! channel)]
> (swap! buffer pop)
> x)))
>
> (defn transparent-buffer [{keys [buffer]}]
> (vec @buffer))
>
> - James
>
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