I have been using CommandLineParser for a while now (and it's changed how I build tools -- thank you!) including in a program with ~50 Verbs (and growing), and since many of the Verbs take common options, I was hoping to extend Options to provide common handling of them.

Simple example: if 15 Verbs take a LogFile option, each of which has a long name ("log-file") and a help description, I can do this now by constant strings to keep them consistent, but if I were able to do:

[AttributeUsage(AttributeTargets.Property)]
public class LogFileOptionAttribute : OptionAttribute
{
    public LogFileOptionAttribute(bool required = false)
        : base("log-file") // I don't use short option names for anything
    {
        HelpText = "Name of the logfile to use for blah blah blah";
        Required = required;
    }
}

and then adorn the actual option with:

public class BlahOptions {
    ...
    [LogFileOption]
    public string LogFileName {get ; set; }
    ...
}

I have easily a dozen of these common options. It's not a huge deal to create constant strings:

    [Option(OPTION_LOGFILE_NAME, HelpText = OPTION_LOGFILE_HELPTEXT)]

but adding this level of abstraction would be more convenient.

If there's a good reason for this class to be sealed, then so be it, but mine doesn't feel like a ridiculous use case. I may well get to 100 verbs for this tool by the time I'm done.