我厚颜无耻地从我找到的(但现在似乎无法检索到)示例博客帖子中删除了几乎所有这些代码,该示例博客帖子演示了如何使用Java的套接字实现来维护简单的IRC连接。
在使用这个例子的时候,我遇到了一个问题,我想加入一系列的频道。我的第一个想法是在服务器变量上存储一个通道矢量,然后在匹配模式时对其进行解构。然而,到目前为止,这并不起作用。如果我将map更改为对write函数的裸调用,则一切正常。然而,映射write函数似乎不起作用,我不知道为什么。有趣的是,如果我将map调用复制并粘贴到运行活动连接的repl中,它就会工作……那么这是因为这发生在cond的范围内吗?裁判有可能被责备吗?我刚刚进入Clojure,所以我仍然在努力弄清楚一些事情。
不再赘述,下面是代码:
(ns irc
(:import (java.net Socket)
(java.io PrintWriter InputStreamReader BufferedReader)))
(def server {:server "irc.example.net"
:port 6667
:channels ["#a" "#b"]})
(def client {:realname "Lambda Bot" :nick "lambdabot"})
(declare conn-handler)
(defn in [a b]
(re-find (re-pattern a) b))
(defn startswith [a b]
(in (str "^" a) b))
(defn connect [server]
(let [socket (Socket. (:server server) (:port server))
in (BufferedReader. (InputStreamReader. (.getInputStream socket)))
out (PrintWriter. (.getOutputStream socket))
conn (ref {:in in :out out})]
(doto (Thread. #(conn-handler conn server)) (.start))
conn))
(defn write [conn msg]
(println msg)
(doto (:out @conn)
(.println (str msg "\r"))
(.flush)))
(defn conn-handler [conn server]
(while (nil? (:exit @conn))
(let [msg (.readLine (:in @conn))]
(println msg)
(cond
(startswith "ERROR :Closing Link:" msg)
(dosync (alter conn merge {:exit true}))
(in " 001 " msg)
;; this guy below doesn't seem to work at all
(map #(write conn (str "JOIN " %)) (:channels server))
;; this guy on the other hand seems to work fine
;;(write conn (str "JOIN " (first (:channels server))))
(startswith "PING" msg)
(write conn (str "PONG " (re-find #":.*" msg)))))))
(defn login [conn user]
(write conn (str "NICK " (:nick user)))
(write conn (str "USER " (:nick user) " 0 * :" (:realname user))))要运行它,您可以简单地调用:(def irc (连接服务器)),然后调用(login irc client)。如有任何帮助,我们不胜感激!谢谢。
发布于 2012-11-12 11:41:47
map是一个惰性操作,也就是说,它直到需要时才会执行。当从repl调用时,repl会导致它求值,因为它需要打印返回值。
您可以使用doall强制执行惰性操作。
(doall (map ... ))使用doseq而不是map会更好。map用于将一组值转换为另一组值,而doseq用于对一组值执行操作,这就是您想要做的事情。
(doseq [ch (:channels server)]
(write conn (str "JOIN " ch)))https://stackoverflow.com/questions/13337729
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