From: LDC - Jairo Eduardo Lopez <jairo@...>
Date: 2007-05-25T01:13:54+09:00
Subject: Ruby, OptionParser and multiple flags

Hello all,

I'm currently writing a small script needed for my lab in which I need to 
parse a few command line arguments in a UNIX like way.

My code goes something like this:

#####
#!/usr/bin/ruby -w

require 'optparse'
require 'ostruct'

opciones = OpenStruct.new
opts = OptionParser.new do |opts|
     opts.on("-u USER", "--uid USER", "UID del usuario.") do |usr|
         opciones.user = usr
     end

     opts.on("-h HOST", "--host HOST", String, "Especifica el servidor. 
Puede ser IP o DNS.") do |h|
         opciones.host = h
     end

     opts.on("-p PORT", "--port PORT", Integer, "Especifica el puerto del 
servidor. Debe ser entero.") do |p|
         opciones.port = p
     end
end

begin
     opts.parse!(ARGV)
rescue Exception => e
     puts e, opts
     exit!
end

#####

When I run the script I run into the problem that if I use various flags, 
and forget to put in the required arguments, some flags are taken as 
arguments. I've read that if I use the coding I've used all three 
flags, the argument should be obligatory.

To better explain, I'll give some examples:

-----
./script.rb -h
missing argument: -h
-----
Works fine.

-----
./script.rb -p
missing argument: -p
-----
Works fine.

-----
./script.rb -h -p 
-----
The script accepts -p as the argument for -h, which shouldn't happen as -p 
is actually a flag.

I'm not sure what the problem is so I need help.

I'm running on a Debian Etch Box i686 with a Ruby 1.8.5 version.

Any help would be greatly appreciated. Thank you all.

-- 
Jairo E. Lopez
Laboratorio Docente de Computacion
Universidad Simon Bolivar