Oh, maybe this as-file method already exists in clojure.contrib, honestly I don't know and don't have the time to search right now,
regards, -- laurent On 8 oct, 16:41, Laurent PETIT <laurent.pe...@gmail.com> wrote: > Suggestion : > > move and generalize the problem by creating an as-file multifn that may take > String, File , and maybe other things later ... > > (defmulti as-file type) > (defmethod as-file String [from] (File. from)) > (defmethod as-file File [from] from) > > (defn mv [from to] > (let [ [from to] (map as-file [from to]) ] > (println "transformed to file")) > > cheers, > > -- > laurent > > 2009/10/8 Robert Stehwien <rstehw...@gmail.com> > > > Here is another question on when you would use a multi-method. I want the > > mv function to accept a java.io.File or a String for either of the two > > parameters and here are the options I came up with: > > > -----(defmulti mv (fn [from to] [(class from) (class to)])) > > (defmethod mv [String String] [from to] (println "Both strings")) > > (defmethod mv [File File] [from to] (println "Both files")) > > (defmethod mv [File String] [from to] (println "File String")) > > (defmethod mv [String File] [from to] (println "String File")) > > > (defn mv2 [from to] > > (let [f (if (= (class from) File) from (File. from)) > > t (if (= (class to) File) from (File. to))] > > (println "transformed to File"))) > > ----- > > > While I find that multi-methods allowing me to do the above exceedingly > > cool, would it be more idomatic to just use the let and create a File if > > passed a String. Am I doing "too much work" for something relatively > > simple. > > > The multi-method does have better (IMHO) errors when passed (mv ["foo"] > > "bar"): > > ----- > > No method in multimethod 'mv' for dispatch value: > > [clojure.lang.LazilyPersistentVector java.lang.String] > > [Thrown class java.lang.IllegalArgumentException] > > ----- > > > This would tell me that I could write another multi-method that could move > > multiple files from different locations passed in as a sequence to one > > destination... which I didn't think I needed but could be pretty handy now > > that I think on it. > > > --Robert --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
