Nope, though thinking further on it, I'm really not a fan of people having to know java's class name encoding scheme for arrays. Personally, I'd prefer writing (array-class String), or have some clojure-specific syntax to denote an array of a class (though some would say clojure has enough syntax as-is).
On Mar 24, 7:49 pm, Frank Siebenlist <frank.siebenl...@gmail.com> wrote: > Nice research - so is it then the reader that doesn't allow us to escape the > "[B" such that we can write it such that it can be interpreted as a symbol [B > ? > > -Frank. > > On Mar 24, 2010, at 7:27 PM, ataggart wrote: > > > > > Ok, after looking into how clojure resolves class literal symbols, it > > turns out it is already smart enough to recognize symbol names that > > start with "["; the problem is it's a pain to type such symbols into > > code. > > > Your code can work this way: > > user=> (defmethod mm (resolve (symbol "[B")) [b] (println "bytes")) > > #<MultiFn clojure.lang.mult...@6ee3849c> > > user=> (mm (.getBytes "a")) > > bytes > > nil > > > In the end though, it turns out to be just another way to call (Class/ > > forName "[B"). > > > On Mar 24, 6:54 pm, ataggart <alex.tagg...@gmail.com> wrote: > >> The java version would look like: > >> Class c = byte[].class; > > >> But since the clojure way to obtain a class is simply to use its name > >> literal, e.g.: > >> user=> (type String) > >> java.lang.Class > >> the only way to get the class of an array would involve either a > >> function call or a change to the reader. And java doesn't make it > >> easy since all array-class stuff, such as Class.isArray(), is native > >> code. The best I've come up with is: > >> user=> > >> (defn #^Class array-class > >> "Returns the Class of an array of component type c" > >> [#^Class c] > >> (when c (class (java.lang.reflect.Array/newInstance c 0)))) > >> user=> (array-class String) > >> [Ljava.lang.String; > >> which appears faster than using Class/forName with a created string. > >> But since one *can* type a literal byte array class in java, I'd > >> imagine there's some way to implement this with bytecode magic, rather > >> than going through java.lang.reflect.Array. > > >> On Mar 24, 3:39 pm, Frank Siebenlist <frank.siebenl...@gmail.com> > >> wrote: > > >>> Right - not very different from the (class (byte-array 1)) that I came up > >>> with in the mean time... all not very clojuresque. > > >>> -FS. > > >>> On Mar 24, 2010, at 3:03 PM, ataggart wrote: > > >>>> For type-hinting #^"[B" works, but for obtaining and passing the class > >>>> to defmethod, the best I can come up with is (Class/forName "[B"). > > >>>> On Mar 24, 11:02 am, Frank Siebenlist <frank.siebenl...@gmail.com> > >>>> wrote: > >>>>> The following repl session shows my attempt to dispatch a multimethod > >>>>> on "type": > > >>>>> ... > >>>>> user> (defmulti mm type) > >>>>> #'user/mm > >>>>> user> (type "a") > >>>>> java.lang.String > >>>>> user> (defmethod mm java.lang.String [s] (println "string")) > >>>>> #<MultiFn clojure.lang.mult...@41e3a0ec> > >>>>> user> (mm "a") > >>>>> string > >>>>> nil > >>>>> user> (type (.getBytes "a")) > >>>>> [B > >>>>> user> (defmethod mm [B [b] (println "bytes")) > >>>>> ; Evaluation aborted. > >>>>> user> (def ba-type (type (.getBytes "a"))) > >>>>> #'user/ba-type > >>>>> user> (defmethod mm ba-type [b] (println "bytes")) > >>>>> #<MultiFn clojure.lang.mult...@41e3a0ec> > >>>>> user> (mm (.getBytes "a")) > >>>>> bytes > >>>>> nil > >>>>> user> > >>>>> ... > > >>>>> It works easily for the string, but for a native java byte array, type > >>>>> (or class) gives me back this "[B", which I'm unable to use as a > >>>>> dispatch value for the defmethod. > >>>>> I can, however, assign the value to a reference and us that to dispatch > >>>>> on successfully - but that feels like a hack. > > >>>>> Is there a way to express the byte array type in a different way than > >>>>> "[B" that would work? > > >>>>> Thanks, Frank. > > >>>> -- > >>>> 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 > > >>>> To unsubscribe from this group, send email to > >>>> clojure+unsubscribegooglegroups.com or reply to this email with the > >>>> words "REMOVE ME" as the subject. > > > -- > > 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 > > > To unsubscribe from this group, send email to > > clojure+unsubscribegooglegroups.com or reply to this email with the words > > "REMOVE ME" as the subject. -- 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 To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
