> Lets say you want to call static method "foo" of a class, > but you don't know which class -- you want this to be > specified at runtime in a parameter. Something like this: > > (defn map-foo [cls coll] > (map cls/foo coll)) ; doesn't work > > As mentioned by others, one approach is to use reflection, > either Java's API or Clojure's (undocumented, > may-change-without-warning) wrapper: > > (defn map-foo [cls coll] > (map #(clojure.lang.Reflector/invokeStaticMethod > cls "foo" (to-array [%])) > coll)) > > (map-foo MyClass [1 2 3 4]) > > This works, but if you're allowed to adjust the requirements > a bit, a better solution is possible. What if your user > called: > > (map-foo #(MyClass/foo %) [1 2 3 4]) > > This can be done without any runtime reflection at all, > which can greatly boost the runtime speed. Also, it's more > flexible: I *told* you to name your method "foo" but > I guess I should have been more explicit. Oh well, no > matter: > > (map-foo #(YourClass/Foo %) [1 2 3 4]) > > Or if your user is using Clojure rather than Java, they > don't even have to use a class: > > (map-foo #(her-do-foo-thing %) [1 2 3 4]) > > or just: > > (map-foo her-do-foo-thing [1 2 3 4]) > > Best of all implementing map-foo is simpler: > > (defn map-foo [f coll] > (map f coll)) > > Which in this trivial example means you can just use 'map' > instead of 'map-foo'. But even in a less trivial example > you may find this approach more workable all around.
Wow, that was a great answer, a thousand thanks!!!! > Now if you were going to do more than one thing on the class > (call static methods foo, bar, and baz, for example) things > get more complicated. Yeah, that was one of constraint for the problem I was trying to solve, I should have mentioned it. - budu --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
