你能在clojure defrecord中指定一个方法的返回类型吗？ [英] Can you specify the return type of a method in a clojure defrecord?

问题描述

我创建了一个应用程序信息接口和类，但是当我审查生成的类的所有方法的返回类型是Object，我可以更改返回类型为String？文档说明类型提示可能与defrecord但不给一个例子，我可以找到的唯一的例子是类型提示字段和方法参数。

I've created an application-info interface and a class but when I review the generated classes the return type for all of the methods is Object, can I change the return type to String? The documentation says type hinting is possible with defrecord but doesn't give an example, the only examples I could find were for type hinting fields and method arguments.

src / com /vnetpublishing.clj

src/com/vnetpublishing.clj

(ns com.vnetpublishing)

(defprotocol ApplicationInfo
  (author [obj])
  (author-email [obj])
  (copyright [obj])
  (app-name [obj])
  (version [obj])
)

src / Physics.clj

src/Physics.clj

(ns Physics)

(defrecord info [] com.vnetpublishing.ApplicationInfo
  (author [this] "Ralph Ritoch")
  (author-email [this] "Ralph Ritoch <root@localhost>")
  (copyright [this] "Copyright \u00A9 2014 Ralph Ritoch. All rights reserved.")
  (app-name [this] "Physics")
  (version [this] "0.0.1-alpha")
)

推荐答案

查看 definterface 宏。
与defprotocol不同，definterface宏提供了一种为方法写入返回类型提示的方法。

Look at definterface macro. Unlike defprotocol, the definterface macro provide a way to write return type hint for methods.

Alan Malloy对此进行了很好的解释此处：

Alan Malloy explain this pretty well here:

协议是用于消费Clojure函数，不是
应该是静态类型的;接口是由
消费的Java类，需要静态类型。

"Protocols are for consumption by Clojure functions, which aren't supposed to be statically typed; interfaces are for consumption by Java classes, which are required to be statically typed."

您可以使用它：

(definterface Test
 (^void returnsVoid [])
 (^int returnsInt [])
 (^long returnsLong [])                                                             
 (^String returnsString [])
 (^java.util.HashMap returnsJavaUtilHashMap []))

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