Design: builder API for parsing args into .NET types

Problem Users who prefer the builder API can’t take advantage of the automatic type parsing available in the attribute api for int, List<T>, etc. Part of the difficulty is that CommandLineApplication, CommandArgument, and CommandOption only provide string-based properties.

Proposal Add CommandOption<T> and CommandArgument<T>.

There is acts as an implicit requirement that values can be parsed to typeof(T).

For custom types, users can provide a custom converter to parse string into typeof(T). CLU will provide parsers for most commonly used types like int, double, bool, etc.

Usage

public static int Main(string[] args)
{
    var app = new CommandLineApplication();

    CommandArgument<int> arg = app.Argument<int>("arg", "argument");
    CommandOption<int> option = app.Option<int>("--arg", CommandOptionType.SingleValue)
        .Accepts().Range(0, 100);

    CommandOption<IPAddress> option2 = app.Option<IPAddress>("--addres", CommandOptionType.SingleValue)
        .UseConverter(val => IPAddress.Parse(val));

    app.OnExecute(() =>
    {
        int[] values = option.Values;
    });

    return app.Execute(args);
}

[natemcmaster]

Just added support for this. Should be available soon in nightly builds and will be in 2.2.0

[peterwurzinger]

Ah, I didn’t think of compositing types - my bad.

Your proposal looks quite good to me tbh, since one is then able to distinguish between a “normal” Argument, where you don’t care about parsing into a .NET-Type, and “special” Arguments which have this abillity by explicitly accessing an additional property.

I just tried to come up with a solution to make it accessible through a common <whatevertype> Values { get; } - Property, but didn’t do too well without bringing the big reflection-hammer.