On Nov 4, 11:49 pm, Baishampayan Ghose <b.gh...@gmail.com> wrote: > On Sat, Nov 5, 2011 at 11:55 AM, Martin DeMello <martindeme...@gmail.com> > wrote: > > What's the cleanest way to run a piece of code if any branch of a cond > > statement succeeded, without relying on the return value of the > > individual clauses not to be nil? > > > For example, if I have the following piece of code that says I can > > only move left or up > > > (cond > > (= dir :left) (move-left) > > (= dir :up) (move-up)) > > > but (move-left) or (move-up) could themselves return nil, is there any > > nice way to check if one of them was called? > > What about something like this - > > (cond > (= dir :left) (move-left) > (= dir :up) (move-up) > :else :nok) > > Or > > (cond > (= dir :left) [(move-left)] > (= dir :up) [(move-up)])
Seconded. Though if you can't easily predict what move-left/move-up might return (ie they might even return :nok) you might need to be more careful. Use a namespaced keyword like :my-current-ns/didnt-do- anything, or a gensym (or a fresh Object) for guaranteed uniqueness: (let [nothing (Object.) cond-result (case dir :left (move-left) :up (move-up) nothing)] (if (identical? nothing cond-result) ...)) -- 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