Make sure the enumeration is in one of the desired states

Question

If I have an enumeration

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

Is it possible to check if an enumeration in one of the desired states is with one check? For example, if I want to check if an enumeration is normal or NormalNoMove, I should always write it like this:

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

This is not a big problem if there are only two values, but there will be more enumeration states, and it would be nice if I only had to change it in one place. Is it possible to make an alum alias that returns true if the enum value is either normal or NormalNoMove? Or do I need to write some kind of helper method to achieve this (extension method?)

Answer 1

Bitwise logic should work with flag enums like this.

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

You can also 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 the 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 wonder if bit-wise flags need to be reviewed here. It appears that “Normal” is the state you want to check, and “NormalNoMove” is based on that. Perhaps your listing should look like this:

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

This way you can check if flow & GameFlow.Normal > 0 is there if you are in a normal state: NormalNoMove just "extends" Normal , so to speak.

Answer 2

Based on the comment on @StringlingWarrior's answer, you can simply create an extension method that will shorten your code:

 public static class GameFlowExtensions { public static bool IsNormal(this GameFlow flow) { return (flow & (GameFlow.Normal | GameFlow.NormalNoMove)) > 0; } } // usage: if (Flow.IsNormal()) 

Answer 3

You can set the variable equal to GameFlow.Normal and GameFlow.NormalNoMove , and then compare the value you have, like this:

 GameFlow NormalOrNormalNoMove = GameFlow.Normal | GameFlow.NormalNoMove; ... if ((Flow & NormalOrNormalNoMove) > 0) { // Your code }