(defmacro plus [] (if … (resolve (symbol "clojure.core/+")) (resolve (symbol "clojure.core/+'"))))
((plus) actual delta) On Mon, Oct 10, 2011 at 4:28 PM, Brian Marick <mar...@exampler.com> wrote: > I may be missing something obvious. > > Midje has a checker that lets users say things like > > (fact (my-computation) => (roughly 15 2)) > > Where the first number in `roughly` is the target number and the second is an > acceptable range around that target. Part of what the checker does in 1.2 is > this: > > (<= expected (+ actual delta)) > > Now, Midje is a service. If the 1.3 user has taken care to use > promoting-to-bignum arithmetic, it would be rude to blow up if `actual` > happens to be a regular integer but adding `delta` to it causes an overflow. > I should use promoting-to-bignum addition. In Clojure 1.3, thats +'. In 1.2, > it's +. > > I can't use the token +' because it doesn't exist in 1.2: > >> java.lang.ClassCastException: clojure.lang.Symbol cannot be cast to >> java.lang.Number (NO_SOURCE_FILE:0) > > > I can't use the token + because that blows up in the boundary case under 1.3 > (but not under 1.2). > > One thought is variations of code like this: > >> (if (clojure-1-3?) >> (def +M +') >> (def +M +) > > This causes amusing results because of the quote. I haven't found a variation > that works. > > So what should a library writer who wants to honor the choices of his users > do? > > > ----- > Brian Marick, Artisanal Labrador > Now working at http://path11.com > Contract programming in Ruby and Clojure > Occasional consulting on Agile > > > -- > 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 -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? -- 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
