Juxtaposition of Java instance methods in Clojure

Question

Is it possible to use juxt in conjunction with methods of a Java object in Clojure?

Basically what I'm trying to achieve is

((juxt .method1 .method2) myinstance)

with .method1 and method2 being instance methods of myinstance, which is an instance of some Java class.

Thanks for your help!

leetwinski · Accepted Answer · 2016-08-25 14:53:46Z

5

or just make a macro for that, which would combine normal juxt behaviour with .method behaviour. Something like this:

user> (defmacro juxt+ [& fns]
        (let [x (gensym)]
          `(fn [~x] ~(mapv #(list % x) fns))))
#'user/juxt+

for example:

(juxt+ .getName (partial str "string val: ") .getAbsolutePath vector)

expands to the following:

(fn*
  ([G__19829]
    [(. G__19829 getName)
     ((partial str "string val: ") G__19829)
     (. G__19829 getAbsolutePath)
     (vector G__19829)]))

in repl:

user> ((juxt+ .getName 
              (partial str "string val: ") 
              .getAbsolutePath 
              vector) 
         (java.io.File. "aaa"))

["aaa" 
 "string val: aaa" 
 "/Users/.../aaa" 
 [#object[java.io.File 0x34c3af49 "aaa"]]]

answered Aug 25, 2016 at 14:53

leetwinski

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superkonduktr · Accepted Answer · 2016-08-25 13:28:34Z

4

Try encapsulating the method calls in anonymous functions:

((juxt #(.method1 %) #(.method2 %)) myinstance)

answered Aug 25, 2016 at 13:28

superkonduktr

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