Check if enum is in one of desired states

Question

If I have enum

    [Flags]
    public enum GameFlow
    {
        Normal = 1,
        NormalNoMove = 2,
        Paused = 4,
        Battle = 8
    }

Is it possible to check if the enum is in either one of desired states with a single check? For example if I'd like to check if enum's is either Normal or NormalNoMove do I always have to write it like this?

if(Flow == GameFlow.Normal || Flow == GameFlow.NormalNoMove)

It's not a big problem if there are only two values but there will be more enum states and it would be nice if I only would have to change it in one place. Is it somehow possible to make an enum alias that would return true if enum value is either Normal or NormalNoMove? Or do I have to write some kind of helper method to achive that(extension method?)

Answer 1

Maybe it can be useful

public static class EnumExtensions
{
    public static bool IsOneOf(this Enum enumeration, params Enum[] enums)
    {
        return enums.Contains(enumeration);
    }
}

// usage:
if(Flow.IsOneOf(GameFlow.Normal, GameFlow.NormalNoMove))

Answer 2

Bitwise logic should work on flag enums like this.

if((Flow & (GameFlow.Normal | GameFlow.NormalNoMove)) > 0)

It's also possible to create enum values that combine other values, as I mention here.

So, in your case:

[Flags]
public enum GameFlow
{
    Normal = 1,
    NormalNoMove = 2,
    Paused = 4,
    Battle = 8,
    AnyNormal = Normal | NormalNoMove
}

bool IsNormal(GameFlow flow)
{
    return (flow & GameFlow.AnyNormal) > 0;
}

And a LINQPad test:

void Main()
{
    IsNormal(GameFlow.Normal).Dump();// True
    IsNormal(GameFlow.NormalNoMove).Dump();// True
    IsNormal(GameFlow.Paused).Dump();// False
    IsNormal(GameFlow.Battle).Dump();// False

    IsNormal(GameFlow.Normal | GameFlow.Paused).Dump();// True
    IsNormal(GameFlow.NormalNoMove  | GameFlow.Battle).Dump();// True
    IsNormal(GameFlow.Paused | GameFlow.Battle).Dump();// False
    IsNormal(GameFlow.Battle | GameFlow.Normal).Dump();// True

}

Based on your comment, I'm wondering if you should revise the bitwise flags here, too. It sounds like "Normal" is a state you want to check for, and "NormalNoMove" builds on that. Maybe your enum should look more like this:

[Flags]
public enum GameFlow
{
    Normal = 1,
    NormalNoMove = Normal | 2,
    Paused = 4,
    Battle = 8
}

That way, you can check whether flow & GameFlow.Normal > 0 to see if you're in either normal state: NormalNoMove just "extends" Normal, so to speak.