任何人都知道缺乏一个枚举泛型约束的一个很好的解决方法吗？ [英] Anyone know a good workaround for the lack of an enum generic constraint?

问题描述

我想要做的是这样的：我有标记结合枚举值

What I want to do is something like this: I have enums with combined flagged values.

public static class EnumExtension
{
    public static bool IsSet<T>( this T input, T matchTo ) 
        where T:enum //the constraint I want that doesn't exist in C#3
    {    
    	return (input & matchTo) != 0;
    }
}

于是我可以这样做：

So then I could do:

MyEnum tester = MyEnum.FlagA | MyEnum.FlagB

if( tester.IsSet( MyEnum.FlagA ) )
    //act on flag a

不幸的C＃泛型约束的地方都没有枚举限制，只有类和结构。 C＃不看枚举作为结构（即使它们是值类型），所以我不能添加扩展类型是这样的。

Unfortunately C#'s generic where constraints have no enum restriction, only class and struct. C# doesn't see enums as structs (even though they are value types) so I can't add extension types like this.

任何人都知道一个解决办法？

Anyone know a workaround?

推荐答案

编辑：这是现在住在UnconstrainedMelody的0.0.0.2版本

（按照要求在我的博客文章的。我已经包括下面的一个独立的答案着想的基本事实枚举限制。）

(As requested on my blog post about enum constraints. I've included the basic facts below for the sake of a standalone answer.)

最好的办法是等待我去 UnconstrainedMelody ^{1 <包括它/ SUP>。这是采用C＃code。与假的约束，如}

The best solution is to wait for me to include it in UnconstrainedMelody¹. This is a library which takes C# code with "fake" constraints such as

where T : struct, IEnumConstraint

和把它变成

where T : struct, System.Enum

通过postbuild一步。

via a postbuild step.

应该不会太难写使用isset ...虽然餐饮为的Int64 和基于 UINT64 基于标志可能是棘手的部分。 （我闻到了一些辅助的方法来了，基本上让我枚举对待任何标志，如果它有一个基本类型 UINT64 ）

It shouldn't be too hard to write IsSet... although catering for both Int64-based and UInt64-based flags could be the tricky part. (I smell some helper methods coming on, basically allowing me to treat any flags enum as if it had a base type of UInt64.)

将你想要的行为，如果你叫

What would you want the behaviour to be if you called

tester.IsSet(MyFlags.A | MyFlags.C)

？如果它检查的所有的指定标志设置？这将是我的期望。

? Should it check that all the specified flags are set? That would be my expectation.

我会尽力做到这一点在回家的路上，今晚......我希望能有有用的枚举方法的快速突击，以获得库到一个可用的标准很快，然后放松了一下。

I'll try to do this on the way home tonight... I'm hoping to have a quick blitz on useful enum methods to get the library up to a usable standard quickly, then relax a bit.

编辑：我不知道关于使用isset 作为名字，顺便说一句。选项​​：

I'm not sure about IsSet as a name, by the way. Options:

• 包含


• 包含


• HasFlag（或HasFlags）


• 使用isset（它肯定是一个选项）

思考的欢迎。我敢肯定，任何事情之前在石头上的设置无论如何这将是一段时间...

Thoughts welcome. I'm sure it'll be a while before anything's set in stone anyway...

¹ 或提交它作为一个补丁，当然...

¹ or submit it as a patch, of course...

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