build-protocol Clojure宏

Question

作为我的previous question的后续，我正在尝试编写一个构建defprotocol的宏

(build-protocol AProtocol
  [(a-method [this]) (b-method [this that])]
  (map (fn [name] `(~(symbol (str name "-method")) [~'this ~'that ~'the-other]))
    ["foo" "bar" "baz"])
  (map (fn [name] `(~(symbol (str name "-method")) [~'_]))
    ["hello" "goodbye"]))

应该扩展到

(defprotocol AProtocol
  (a-method [this])
  (b-method [this that])
  (foo-method [this that the-other])
  (bar-method [this that the-other])
  (baz-method [this that the-other])
  (hello-fn [_])
  (goodbye-fn [_]))

我的尝试是：

(defmacro build-protocol [name simple & complex]
  `(defprotocol ~name ~@simple
     ~@(loop [complex complex ret []]
         (if (seq complex)
           (recur (rest complex) (into ret (eval (first complex))))
           ret))))

和扩展(macroexpand-1 '(...))

(clojure.core/defprotocol AProtocol
  (a-method [this])
  (b-method [this that])
  (foo-method [this that the-other])
  (bar-method [this that the-other])
  (baz-method [this that the-other])
  (hello-method [_])
  (goodbye-method [_]))

我对eval并不是很满意。而且，map表达式相当难看。有没有更好的方法？欢迎任何评论。

一旦我让它正常工作，我将为(build-reify ...)做一个类似的宏。我正在编写一个相当大的Swing应用程序，并且有几个组件(JButton、JCheckBoxes等)。它们具有几乎相同的方法签名和操作。

Answer 1

我觉得你做得颠倒了。首先指定"-method“内容，包装在某种容器中，以便构建协议知道是什么，并让它在宏内执行映射。例如：

(build-protocol AProtocol
  {[this that whatever] [foo bar baz],
   [_] [hello goodbye]}
  ; a-method and b-method...
)