On Fri, Nov 5, 2010 at 1:39 AM, Mike Meyer < mwm-keyword-googlegroups.620...@mired.org> wrote:
> It seems like the polymorphism of protocols breaks inside the > methods. This is a problem for having a function that's polymorphic > between an object and a container of the same objects. > > For instance: > > user=> (defprotocol Tune (tweek [this])) > Tune > user=> (deftype Knob [name] Tune (tweek [this] (println "Tweeked" name))) > user.Knob > user=> (def base (Knob. "base")) > #'user/base > user=> (tweek base) > Tweeked base > nil > user=> (def treble (Knob. "treble")) > #'user/treble > user=> (tweek treble) > Tweeked treble > nil > user=> (deftype Box [& knobs] Tune (tweek [this] (for [knob knobs] (tweek > knob)))) > this vector is not an argument list but a field list, so you are defiing to fields, one named & and one named knobs. Try to evaluate (.name (.knobs (Box. base treble))) and you'll see that knobs only holds treble. if you fix it: (deftype Box [knobs] Tune (tweek [this] (for [knob knobs] (tweek knob)))) then: (tweek (Box. [base treble])) will work as expected. If you really want var-args, you just have to write a factory fn (defn box [& knobs] (Box. knobs)) hth, Christophe -- 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
