RCR 130: Provide a common ancestor for GetoptLong error classes

This is a legacy RCR from Ruby Garden, submitted by anonymous. Matz has declared these RCRs obsolete, and asked that their authors resubmit them in the new format.

Witha little tweaking, the exception mechanism of GetoptLong could be made a lot more convenient,

(RCR imported from old format)

As I understand it the parsing stage of GetoptLong can throw one of four errors:

• GetoptLong::AmbigousOption
• GetoptLong::NeedlessArgument
• GetoptLong::MissingArgument
• GetoptLong::InvalidOption

The annoyance? They don't have a common yet unique parent. They all inherit from StandardError instead of, ideally, inheriting from something along the lines of a GetoptLong::Error. So, instead of being able to do:

begin

  GetoptLong.new().set_options(
                               [ ... ]
                               ).each ...

rescue GetoptLong::Error

  printHelp()
  exit 1

end

I seem to have to do something like:

begin

  GetoptLong.new().set_options(
                               [ ... ]
                               ).each ...

rescue GetoptLong::AmbigousOption, GetoptLong::NeedlessArgument,

       GetoptLong::MissingArgument, GetoptLong::InvalidOption
  printHelp()
  exit 1

end

That feels a little clumsy. I wonder if there is some reasoning behind this or would it make sense to change GetoptLong so that there is a catch-all parent class for the errors that it can throw?

(RCR imported from old format)

(RCR imported from old format)