重命名导入的静态函数有什么问题？ [英] what's wrong with renaming imported static functions?

问题描述

考虑以下Scala代码：

Consider the following Scala code:

    object MainObject {

    def main(args: Array[String]) {

      import Integer.{
        parseInt => atoi
      }

      println(atoi("5")+2);

      println((args map atoi).foldLeft(0)(_ + _));

  }

第一个println工作正常，输出7，但第二个，尝试映射函数atoi的字符串数组不起作用，错误值atoi不是对象java.lang.Integer的成员

First println works fine and outputs 7, but the second one, attempting to map array of strings against a function atoi doesn't work,with error "value atoi is not a member of object java.lang.Integer"

什么是差异？

推荐答案

这是因为它无法分辨使用哪个atoi。 parseInt（String）和parseInt（String，int）有两种可能性。来自REPL：

This is because it can't tell which atoi to use. There are two possibilities parseInt(String) and parseInt(String, int). From the REPL:

scala> atoi <console>:7: error: ambiguous reference to overloaded definition, both method parseInt in object Integer of type (x$1: java.lang.String)Int and  method parseInt in object Integer of type (x$1: java.lang.String,x$2: Int)Int match expected type ?
       atoi

您需要具体说明使用哪一个，这将有效：

You need to say specifically which one to use, this will work:

println((args map ( atoi(_))).foldLeft(0)(_ + _));

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