我可以在Ruby中动态调用数学运算符吗? [英] Can I dynamically call a math operator in Ruby?

问题描述

红宝石里有这样的东西吗?

Is there something like this in ruby?

send(+, 1, 2)

我想让这段代码看起来不太多余

I want to make this piece of code seem less redundant

if op == "+"
  return arg1 + arg2
elsif op == "-"
  return arg1 - arg2
elsif op == "*"
  return arg1 * arg2
elsif op == "/"
  return arg1 / arg2

推荐答案

是的，只需使用 send (或者更好的是， public_send )，就像这样:

Yup, simply use send (or, better yet, public_send) like so:

arg1.public_send(op, arg2)

之所以可以使用它，是因为Ruby中的大多数运算符(包括+，-，*，/，

This works because most operators in Ruby (including +, -, *, /, and more) simply call methods. So 1 + 2 is the same as 1.+(2).

如果op是用户输入的内容，您可能还希望将其列入白名单. %w[+ - * /].include?(op)，否则用户将能够调用任意方法(这是一个潜在的安全漏洞).

You may also want to whitelist op if it’s user input, e.g. %w[+ - * /].include?(op), as otherwise the user will be able to call arbitrary methods (which is a potential security vulnerability).

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