在Scala中将字符串转换为运算符 [英] Convert string into operator in Scala

问题描述

如何将Scala中的字符串转换为相应的运算符? 给定两个整数和字符串"+"，我想要将这两个整数相加的结果.

How can I convert a string in Scala into a corresponding operator? Given two integers and the string "+" I want the result of adding these two integers.

推荐答案

最后一个问题很简单:

def applyOperator(x: Int, y: Int, operator: String) = operator match {
  case "+" => x + y
  case "-" => x - y
  ...
}

您可以尝试使用Twitter的Eval库或反射，但是鉴于更简单的解决方案，我不建议您使用它.

You could try using Twitter's Eval library or reflection, but I wouldn't recommend it given the simpler solution.

对于第一个问题:运算符本身不是值，因此您不能将字符串转换为运算符".但是您可以接近:将字符串转换为一个函数，该函数将添加(或减去等)其参数:

For the first question: operators themselves aren't values, so you can't "convert a string into an operator". But you can come close: convert a string into a function which will add (or subtract, etc.) its arguments:

def stringToOperator(operator: String): (Int, Int) => Int = operator match {
  case "+" => _ + _
  case "-" => _ - _
  ...
}

您甚至可以泛化它，使其不仅适用于整数:

You can even generalize it a bit to work not just on integers:

def stringToOperator[A: Numeric](operator: String): (A, A) => A = operator match { ... }

(这显然也适用于第一个答案.)

(This also applies to the first answer in the obvious way.)

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