2

在使用Clojure 代理时，fns传递给代理应该覆盖现有方法，或者它们是否与super.method()?

在下面的代码中， RequestHandler.get() 与代理一起被调用get []。

;see: http://github.com/paulosuzart/JTornado
(ns org.ctornadoweb)
(import '(org.jtornadoweb Web$RequestHandler))
(import '(org.jtornadoweb HttpServer Web$Application))


(let [myHandler (proxy [Web$RequestHandler] [] 
                  (get [] 
                    (.write "Hi CLJ"))
                  (post []
                    (.write "POST")))]

(.listen
  (HttpServer.  
    (.add (Web$Application.) "/" (class myHandler))
    false nil false) 8089))

编译/继承版本也是如此：

; Starts a JTornado HTTP Server and a sample RequestHandler.
; Bit verbose due to compilation directives. Recommendation is to generate 
; a set of macros to hide this.
(ns org.ctornadoweb
; Compiled and implements a static main method to start the server
  (:import (org.jtornadoweb HttpServer)
           (org.jtornadoweb.Web$Application)
           (org.jtornadoweb.Web$RequestHandler))
  (:gen-class :prefix "server-"))

(gen-class
 :name org.ctornadoweb.MyHandler
 :extends org.jtornadoweb.Web$RequestHandler
 :prefix "do")

(defn do-get [this]
  "Handles the HTTP GET method"
  (.write "hello clojure"))
(defn do-post [this]
  "Handles the HTTP POST method"
  (.write (.getArgument "name" "default" false)))


(defn server-main []
  "main method"
 (.listen
  (org.jtornadoweb.HttpServer.
   (.add (org.jtornadoweb.Web$Application.) "/" org.ctornadoweb.MyHandler)
     false nil false) 8089))

;use (compile 'org.ctornadoweb)

跟踪显示代理 get 被调用，然后是 super.get，这会引发（默认情况下）异常。

HTTP 405: Method Not Allowed 
    at org.jtornadoweb.Web$RequestHandler.get(Web.java:72)
    at org.ctornadoweb.proxy$org.jtornadoweb.Web$RequestHandler$0.get(Unknown Source)

我试图找到一些关于 Clojure 代理的实际行为的词。有人可以提供帮助吗？

4

1 回答 1

11

不，super 方法不会被自动调用，尽管您可以使用 . 显式调用它proxy-super。

以下测试用例显示了应有的工作：

user=> (def foo 
         (proxy [java.util.ArrayList] [] 
           (clear [] (println "not clearing"))))
#'user/foo
user=> (.size foo)
0
user=> (.add foo "hi")
true
user=> (.add foo "bye")
true
user=> (.size foo)
2
user=> (.clear foo)
not clearing
nil
user=> (.size foo)
2

如果super.clear()被调用，大小将显示为 0。

于 2010-07-19T06:08:18.880 回答