gistfile1.clj

(defn proxy-meta
  "Returns an anonymous class instance, constructed with the file on the path
indicated by `infile', annotated with metadata indicating the filename used to
construct the instance. Optional `moremeta' is a single map containing any
additional metadata to add to the instance."
  [infile & [moremeta]]
  (let [metadata (merge {:filename infile} moremeta)]
    (proxy [PdfReader clojure.lang.IObj] [infile]
      (withMeta [newmeta] (proxy-meta infile newmeta))
      (meta [] metadata))))

(defmacro proxy-foo [class]
  `(fn make# [infile# & [moremeta#]]
     (let [metadata# (merge {:filename infile#} moremeta#)]
       (proxy [~class clojure.lang.IObj] [infile#]
         (withMeta [newmeta#] (make# infile# newmeta#))
         (meta [] metadata#)))))