使用 diff args 覆盖函数时出现不支持的绑定形式错误

Question

我是 Clojure 新手。我定义了以下协议

(ns com.mycompany.protocols.tools)

(defprotocol Tool
   (test-ov [this] [this user-id]))

我尝试了两种实现方式。

实现方式1：

(ns com.mycompany.resources.tools

   (:require [com.mycompany.protocols.tools :as proto]))

(deftype MyTool [config]
   proto/Tool

 (test-ov
   ([this user-id]
       1111 )
 ([this]
   (test-ov this nil)))

......

我遇到错误

    LOAD FAILURE for com.mycompany.myservice.resources.utils
clojure.lang.Compiler$CompilerException: java.lang.Exception: Unsupported binding form: 1111, compiling:(com/mycompany/resources/mytool.clj:198:1)
                    java.lang.Exception: Unsupported binding form: 1111
                                        ......

实现方式2：

(ns com.mycompany.resources.tools

   (:require [com.mycompany.protocols.tools :as proto]))

(deftype MyTool [config]
   proto/Tool

(test-ov
   [this user-id]
       1111 )

(test-ov
   [this]
      (test-ov this nil))

......

我遇到错误

    LOAD FAILURE for com.mycompany.test.myservice.resources.utils
clojure.lang.Compiler$CompilerException: java.lang.RuntimeException: Unable to resolve symbol: test-ov in this context, compiling:(com/mycompany/myservice/resources/mytool.clj:335:6)
             java.lang.RuntimeException: Unable to resolve symbol: test-ov in this context

                                            ......

那么如何从定义了协议的“原始”函数中调用重写函数呢？请帮忙。谢谢。

Answer 1

根据defprotocol的文档，第二种方法是正确的：

(deftype MyTool [config]
   proto/Tool
   (test-ov [this user-id] 1111)
   (test-ov [this] (test-ov this nil)))

问题在于调用

(test-ov this nil)

，因为符号

test-ov

在此上下文中未解析。要么写

(proto/test-ov this nil)

要么在 require 形式中显式引用 var：

(:require [com.mycompany.protocols.tools :as proto :refer [test-ov])