Hi Meikel,
On 25 Jul 2011, at 22:46, Meikel Brandmeyer wrote:
> Am 25.07.2011 um 23:12 schrieb Sam Aaron:
>
> Since this is callback based, you can't return a value. Do you want more
> something like a polling solution? Then you'll have to roll your own with an
> atom and a clojure.lang.PersistentQueue.
Sorry, I should have been more specific. The callback-based watchers are cool,
but I don't believe they specifically address my problem (which I don't believe
I sufficiently explained from the outset).
Hopefully this is a more succinct and specific description. Is there a way to
write the following in a thread safe manner without using a transaction:
(def a (ref 1))
(defn update-and-check-whether-modified?
[update-fn]
(let [changed? (dosync
(let [old-a @a
new-a (alter a update-fn)]
(not= old-a new-a)))]
changed?))
Sam
---
http://sam.aaron.name
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