Question

For the sake of example, suppose I’ve wrapped a StringBuilder in a function so I can use it more easily in Clojure. I can easily make the no-arg version of the function call toString on the buffer e.g.

(defn builder
  ([^StringBuilder sb]
     (fn
       ([] (.toString sb))
       ([& args]
          (doseq [arg args]
            (.append sb arg)))))
  ([] (builder (StringBuilder.))))

This is perfectly workable, however, I wonder how I could just override .toString() on the function itself so I could return the state of the StringBuilder or any other object that I have closed over.

Answer 1

You could try using https://github.com/technomancy/serializable-fn, which makes functions include their closed-over scope when they print. It will print the pr-str of the stringbuilder, though, which may or may not be exactly what you want.