Display A Help Screen

Mapping a method with HelpOptionAttribute will allow the parser to display a help screen when parsing rule are violated.

class Options
{
  [Option("p", "person-to-greet", Required=true, HelpText="The person to greet.")]
  public string PersonToGreet { get; set; }

  [HelpOption]
  public string GetUsage()
  {
    return "Please read user manual!" + Environment.NewLine;
  }
}

In this sample the -p|--person-to-great option is mandatory. Omitting it will cause the parser to display the string returned by Options::GetUsage().

When mapping a method with HelpOption the are only few constraint to respect. The method must be an instance method, it have to return a string and accept no parameters. The name can be the one that you prefer.

Using HelpText class

The CommandLine.Text namespace contains helper types to make easy the render of the help screen.

class Options
{
  [Option("p", "person-to-greet", Required=true, HelpText="The person to greet.")]
  public string PersonToGreet { get; set; }

  [HelpOption]
  public string GetUsage()
  {
    var help = new HelpText {
    Heading = new HeadingInfo("<<app title>>", "<<app version>>"),
      Copyright = new CopyrightInfo("<<app author>>", 2012),
      AdditionalNewLineAfterOption = true,
      AddDashesToOption = true
    };
    help.AddPreOptionsLine("<<license details here.>>");
    help.AddPreOptionsLine("Usage: CSharpTemplate -tSomeText --numeric 2012 -b");
    help.AddOptions(this);
    return help;
  }
}

[TO BE COMPLETED...]