Question

作为previous question的后续内容，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"]))

应扩展为

(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：

(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并不满意。此外，map表达式非常难看。有没有更好的办法？欢迎任何和所有评论。

一旦我开始工作，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 s，JCheckBox es等），它们具有几乎相同的方法签名和操作。

Answer 1

我认为你是颠倒了。首先指定“-method”的东西，包装在某种容器中，这样build-protocol知道什么是什么，并让它在宏内部进行映射。 e.g：

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

构建协议Clojure宏

1 个答案: