Help text not displaying available Enum string values, when property type is Enum[] about powerargs

[adamabdelhamed]

PowerArgs is even more clever than you think (just kidding). You don't need to make your argument an Enum[] to use flags support. The comma separated syntax works even with your standard enum. And you can use Enum.HasFlag(theFlag) to test for flags in your code.

I have an example in this test:

    public enum EnumWithFlags
    {
        Zero = 0,
        One = 1,
        Two = 2,
        Four = 4,
        Eight = 8,
        Sixteen = 16,
    }

    public class EnumArgsWithFlags
    {
        public EnumWithFlags Option { get; set; }
    }

    [TestMethod]
    public void TestEnumWithFlags()
    {
        var args = new string[] { "-o", "Zero,One,Two" };
        var parsed = Args.Parse<EnumArgsWithFlags>(args);
        Assert.AreEqual(EnumWithFlags.Zero | EnumWithFlags.One | EnumWithFlags.Two, parsed.Option);
    }

[Geraint87]

Interesting!

What about Enums where you don't want them to be combinable? What do you think about an amended ArgRevivers.ReviveEnum(Type t, string value, bool ignoreCase):

From:

 if (value.Contains(","))
            {
                int ret = 0;
                var values = value.Split(',').Select(v => v.Trim());
                foreach (var enumValue in values)
                {
...

To:

 if (value.Contains(","))
            {
                if (!t.HasAttr<FlagsAttribute>())
                {
                    System.Text.StringBuilder stringBuilder = new System.Text.StringBuilder();

                    stringBuilder.AppendLine("You cannot specify multiple values for type " + t.Name);
                    stringBuilder.AppendLine("To allow multiple values, " + t.Name + " must be decorated with the [Flags] attribute.");
                    stringBuilder.AppendLine("See MSDN for further details:");
                    stringBuilder.AppendLine(@"http://msdn.microsoft.com/en-us/library/system.flagsattribute(v=vs.110).aspx");
                    stringBuilder.AppendLine();
                    stringBuilder.AppendLine("Options are " + string.Join(", ", Enum.GetNames(t)));

                    throw new ValidationArgException(stringBuilder.ToString());
                }

                int ret = 0;
                var values = value.Split(',').Select(v => v.Trim());
                foreach (var enumValue in values)
                {
...

Or is this sort of check something that would be better placed in a custom Validator/Reviver instead?

(The message doesn't necessarily have to be that verbose)

[adamabdelhamed]

I'd rather not add more restrictions. I personally have never used that FlagsAttribute, and I can imagine that others might not be either.

Like you said, you could build a [NoFlags] validator that explicitly turns off flag support for an enum. That might be a better approach.