小编Rag*_*gge的帖子

对我来说,我遇到了一个看似与clojure记录有关的略微令人惊讶的行为.

设置如下:

1. 一个名称空间定义记录类型:

   (ns defrecordissue.arecord)
   
   (defrecord ARecord [])
   

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2. 另一个命名空间定义了一个协议,并将其扩展为1中定义的记录类型:

   (ns defrecordissue.aprotocol
     (:require [defrecordissue.arecord])
     (:import [defrecordissue.arecord ARecord]))
   
   (defprotocol AProtocol
     (afn [this]))
   
   (extend-protocol AProtocol
     ARecord
     (afn [this] 42))
   

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3. 第三个命名空间构造记录的实例并调用记录上的协议功能.

   (ns defrecordissue.aot1
     (:require [defrecordissue.aprotocol]
               [defrecordissue.arecord]))
   
   (defrecordissue.aprotocol/afn (defrecordissue.arecord/->ARecord))
   

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编译defrecordissue.aot1命名空间时,在我使用的情况下 lein compile defrecordissue.aot1,编译失败,出现以下异常:

Exception in thread "main" java.lang.IllegalArgumentException: No implementation of method: :afn of protocol: #'defrecordissue.aprotocol/AProtocol found for class: defrecordissue.arecord.ARecord, compiling:(aot1.clj:5:1)
    at clojure.lang.Compiler$InvokeExpr.eval(Compiler.java:3463)
    at clojure.lang.Compiler.compile1(Compiler.java:7153)
    at clojure.lang.Compiler.compile(Compiler.java:7219)
    at clojure.lang.RT.compile(RT.java:398)
    at clojure.lang.RT.load(RT.java:438)
    at clojure.lang.RT.load(RT.java:411)
    at clojure.core$load$fn__5018.invoke(core.clj:5530)
    at clojure.core$load.doInvoke(core.clj:5529)
    at clojure.lang.RestFn.invoke(RestFn.java:408)
    at clojure.core$load_one.invoke(core.clj:5336)
    at clojure.core$compile$fn__5023.invoke(core.clj:5541)
    at …