在 C # 中检查 Type instance 是否为可空枚举

在 C # 中，如何检查 Type 是否为可空枚举比如

Type t = GetMyType();
bool isEnum = t.IsEnum; //Type member
bool isNullableEnum = t.IsNullableEnum(); How to implement this extension method?

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EDIT: I'm going to leave this answer up as it will work, and it demonstrates a few calls that readers may not otherwise know about. However, Luke's answer is definitely nicer - go upvote it :)

You can do:

public static bool IsNullableEnum(this Type t)
{
return t.IsGenericType &&
t.GetGenericTypeDefinition() == typeof(Nullable<>) &&
t.GetGenericArguments()[0].IsEnum;
}

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public static bool IsNullable(this Type type)
{
return type.IsClass
|| (type.IsGeneric && type.GetGenericTypeDefinition == typeof(Nullable<>));
}

I left out the IsEnum check you already made, as that makes this method more general.

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See http://msdn.microsoft.com/en-us/library/ms366789.aspx

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最佳答案

public static bool IsNullableEnum(this Type t)
{
Type u = Nullable.GetUnderlyingType(t);
return (u != null) && u.IsEnum;
}

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As from C# 6.0 the accepted answer can be refactored as

Nullable.GetUnderlyingType(t)?.IsEnum == true

The == true is needed to convert bool? to bool