如何在 Ruby 中实现枚举? [英] How to implement Enums in Ruby?

问题描述

在 Ruby 中实现枚举习语的最佳方法是什么?我正在寻找可以使用(几乎)像 Java/C# 枚举的东西.

解决方案

两种方式.符号(:foo 符号)或常量(FOO 符号).

当你想提高可读性而不用文字字符串乱扔代码时，符号是合适的.

postal_code[:minnesota] = "MN";postal_code[:new_york] = "纽约";

当您具有重要的潜在价值时，常量是合适的.只需声明一个模块来保存您的常量，然后在其中声明常量.

模块 Foo酒吧 = 1巴兹 = 2企业 = 4结尾标志 = Foo::BAR |Foo::BAZ # 标志 = 3

于 2021-01-17 添加

如果您正在传递枚举值(例如，将其存储在数据库中)并且您需要能够将值转换回符号，则可以使用两种方法的混搭

COMMODITY_TYPE = {货币:1，投资:2，}定义商品类型字符串(值)COMMODITY_TYPE.key(值)结尾COMMODITY_TYPE[:货币]

这种方法的灵感来自于 andrew-grimm 的回答 https://stackoverflow.com/a/5332950/13468

我还建议您通读这里的其余答案，因为有很多方法可以解决这个问题，而且实际上归结为您关心的其他语言枚举的内容

What's the best way to implement the enum idiom in Ruby? I'm looking for something which I can use (almost) like the Java/C# enums.

解决方案

Two ways. Symbols (:foo notation) or constants (FOO notation).

Symbols are appropriate when you want to enhance readability without littering code with literal strings.

postal_code[:minnesota] = "MN"
postal_code[:new_york] = "NY"

Constants are appropriate when you have an underlying value that is important. Just declare a module to hold your constants and then declare the constants within that.

module Foo
  BAR = 1
  BAZ = 2
  BIZ = 4
end
 
flags = Foo::BAR | Foo::BAZ # flags = 3

Added 2021-01-17

If you are passing the enum value around (for example, storing it in a database) and you need to be able to translate the value back into the symbol, there's a mashup of both approaches

COMMODITY_TYPE = {
  currency: 1,
  investment: 2,
}

def commodity_type_string(value)
  COMMODITY_TYPE.key(value)
end

COMMODITY_TYPE[:currency]

This approach inspired by andrew-grimm's answer https://stackoverflow.com/a/5332950/13468

I'd also recommend reading through the rest of the answers here since there are a lot of ways to solve this and it really boils down to what it is about the other language's enum that you care about

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