Posted to the ruby-talk list by Ara T Howard
============================================
most of my standalone production code looks like this

   % cat foo

   module Foo
     class Main
       ...
     end
   end

   Foo::Main.run(ARGV, ENV) if __FILE__ == $0


that way foo runs as a script.  however the code can be
re-used in this way too

   % cat bar

   require 'foo'

   module Bar
     class Main < Foo::Main
       argv << '--foo-option=42'
       env['foo_env'] = 42
       super(argv, env)
     end
   end

   Bar::Main.run(ARGV, ENV) if __FILE__ == $0


or in this way:

   foo = Foo::Main.new '--key=val --k2-v2'

etc.

basically i re-use top-level code as libs sometimes and then
it's important that two bits of code aren't fighting over
ARGV/ENV.