Example usage of OptionParser with type safety.

OptionParserExample.rb

require 'optparse'

first = last = nil

OptionParser.new do |opts|
  opts.on '-s', '--start=LINE', Integer, 'Start line' do |v|
    first = v
  end

  opts.on '-e', '--end=LINE', Integer, 'End line' do |v|
    first = v
  end
end.parse! ARGV

p first, first.class, last, last.class