delegate_proxy.clj

;; This is very buggy.  Barely works at all.

(defmacro delegate-proxy [bases args delegate & user-methods]
  (let [x (gensym "delegate_")
        user-method-names (set (map first user-methods))
        args-map (reduce (fn [tbl meth]
                           (update-in tbl [(symbol (.getName meth))
                                           (count (.getParameterTypes meth))]
                                      conj
                                      (.getParameterTypes meth)))
                         {}
                         (for [base bases, m (.getMethods (resolve base))] m))]
    `(let [~x ~delegate]
       (proxy ~bases ~args
         ~@user-methods
         ~@(for [[mname arg-counts] args-map
                 :when (not (user-method-names mname))]
             `(~mname ~@(for [arg-count (keys arg-counts)]
                          (let [args (map #(symbol (str 'x %))
                                          (range arg-count))]
                            `([~@args]
                              (. ~x ~mname ~@args))))))))))

(def dp-map (delegate-proxy [clojure.lang.IPersistentMap] []
                            {:a :b, :c :d}
                            (empty [] {:not :empty})))

(conj dp-map [:x :y])
;=> {:x :y, :a :b, :c :d}

(empty dp-map)
;=> {:not :empty}

gistfile2.txt