将枚举转换为基础类型

Question

我有一个枚举如下

type Suit =
    |Clubs = 'C'
    |Spades = 'S'
    |Hearts = 'H'
    |Diamonds = 'D'

如果给定枚举值，如何获取基础char值？ 例如，我有Suit.Clubs并希望得到'C'

Answer 1

作为另一种选择

type Suit =
    |Clubs = 'C'
    |Spades = 'S'
    |Hearts = 'H'
    |Diamonds = 'D'

let c = Suit.Clubs
let v : char = LanguagePrimitives.EnumToValue c

EDITED： 不同方法的比较：

type Suit =
    |Clubs = 'C'
    |Spades = 'S'
    |Hearts = 'H'
    |Diamonds = 'D'

let valueOf1 (e : Suit) = LanguagePrimitives.EnumToValue e
let valueOf2 (e : Suit) = unbox<char> e
let valueOf3 (e : Suit) = (box e) :?> char

并在引擎盖下：

.method public static 
    char valueOf1 (
        valuetype Program/Suit e
    ) cil managed 
{
    // Method begins at RVA 0x2050
    // Code size 3 (0x3)
    .maxstack 8

    IL_0000: nop
    IL_0001: ldarg.0
    IL_0002: ret
} // end of method Program::valueOf1


.method public static 
    char valueOf2 (
        valuetype Program/Suit e
    ) cil managed 
{
    // Method begins at RVA 0x2054
    // Code size 13 (0xd)
    .maxstack 8

    IL_0000: nop
    IL_0001: ldarg.0
    IL_0002: box Program/Suit
    IL_0007: unbox.any [mscorlib]System.Char
    IL_000c: ret
} // end of method Program::valueOf2

.method public static 
    char valueOf3 (
        valuetype Program/Suit e
    ) cil managed 
{
    // Method begins at RVA 0x2064
    // Code size 13 (0xd)
    .maxstack 8

    IL_0000: nop
    IL_0001: ldarg.0
    IL_0002: box Program/Suit
    IL_0007: unbox.any [mscorlib]System.Char
    IL_000c: ret
} // end of method Program::valueOf3

Answer 2

您可以使用LanguagePrimitives模块中的功能：

// Convert enum value to the underlying char value
let ch = LanguagePrimitives.EnumToValue Suit.Clubs

// Convert the char value back to enum
let suit = LanguagePrimitives.EnumOfValue ch

编辑：我在第一次尝试回答时没有看到这些功能，所以我首先建议使用：

unbox<char> Suit.Clubs

这比 ildjarn 在评论中建议的要短，但它有同样的问题 - 没有检查你实际上是否转换为正确的类型。使用EnumToValue，您不能犯这个错误，因为它总是返回正确的基础类型的值。