Nim中的字符串枚举类型？

问题描述

是否可以为字符串定义类枚举类型？我了解枚举，但在这种情况下不想使用枚举，我想像只是字符串一样使用它。

type Blog = object
  text:     string
  priority: "low" | "normal" | "high"

echo Blog(text: "something...",priority: "high")

解决方法

枚举可以附加一个字符串值。转换器可以用于将字符串自动解析为枚举。示例（playground）：

import strutils  # for parseEnum

type
  Priority = enum
    pLow = "low",pNormal = "normal",pHigh = "high"
  Blog = object
    text:     string
    priority: Priority

converter toPriority(s: string): Priority = parseEnum[Priority](s)

echo Blog(text: "something...",priority: "high")
#note that parseEnum is style insensitive
echo Blog(text: "something...",priority: "LOW")
try:
  echo Blog(text: "something...",priority: "medium")
except:
  echo getCurrentExceptionMsg()

输出：

(text: "something...",priority: high)
(text: "something...",priority: low)
invalid enum value: medium

类型定义和转换器可以在诸如以下的宏中自动化：

stringEnum:
  Priority = ["low","medium",high"]

将左侧宏的实现作为练习：）