In my case I can't use memoize because I need to supply the cache map - that in turn is stored on another object so it can be invalidated by events outside my control.
On 30 August 2014 20:00, Ray Miller <r...@1729.org.uk> wrote: > On 30 August 2014 06:26, Colin Fleming <colin.mailingl...@gmail.com> > wrote: > > > > I want to use a map to cache values based on a key. I'm planning to use > an > > atom for this. My basic operation is "give me the value for this key" - > if > > the value exists in the map then that value should be returned, > otherwise a > > new value should be calculated, inserted in the map and then returned. My > > plan is to implement something like the following: > > > > > > (defn ensure [cache key] > > (if (contains? cache key) > > cache > > (assoc cache key (calc-value key)))) > > > > (let [value (get (swap! cache ensure key) key)] > > ... do my thing with value ...) > > Why not just use memoize? > > (def calc-value (memoize (fn [key] ...)) > > If you need more control over the cache, check out core.memoize (which > builds on top of core.cache). > > Ray. > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
