有没有办法让C＃编译器发出一个错误，如果一个开关（enum_val）缺少一个case语句？ [英] Is there a way to get the C# compiler to emit an error if a switch(enum_val) is missing a case statement?

问题描述

我才意识到我添加了一个价值在我枚举必须处理的价值观的名单，但我没赶上，直到运行时。我知道C＃编译器真的很强大，当谈到反思和类型的反省，所以我在想，如果有一种方法来强制开关 / 情况语句以涵盖所有可能的枚举值？

I just realized I added a value to the list of "must-handle" values in my enum, but I didn't catch it until runtime. I know the C# compiler is really powerful when it comes to reflection and introspection of types, so I was wondering if there was a way to force a switch/case statement to cover all possible enum values?

例如：

enum Colors
{
   Red,
   Blue,
   Green,
   Yellow
};

Colors c = ...;

switch (c)
{
   case Colors.Red:  // No error, Red is a Color
      break;
   case Colors.Blue:
   case Colors.Green:  // No error, Blue and Green handled as well
      break;
}  // whoops! "error: 'Colors.Yellow' unhandled"
   // or even, "error: no 'default' and 'Colors.Yellow' unhandled"

我想一个编译时的解决方案。

I want a compile-time solution.

推荐答案

刚刚抛出（双关语是无意的）这一点，你可以用一个字典（ Func键＆LT取代的switch-case; 为例）：

Just by throwing (pun unintended) this out, you can replace the Switch-Case with a dictionary (Func<int,int> as an example):

Dictionary<Colors,Func<int,int>> d = new Dictionary<Colors, Func<int, int>>();
d.Add(Colors.Red, (x) => x+1);
d.Add(Colors.Blue, (x) => x+1);
d.Add(Colors.Green, (x) => x+1);
foreach (Colors color in Enum.GetValues(typeof(Colors)))
{
    if (!d.ContainsKey(color))
    {
        throw new Exception("Poor color " + color + " ignored");
    }
}

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