version_sort.rb

class Array
  def version_sort
    return self.sort {|a,b| my_comparison(a, b) }
  end
  #split each string by - or . and then sort by those parts
  def my_comparison(left, right) #returns -1 or 0 or 1
    left_array = left.split(/[-\.]/) #left array
    right_array = right.split(/[-\.]/) #right array
    left_array.pop
    right_array.pop
    while left_array.size < 4
      left_array.push("0")
    end
    while right_array.size < 4
      right_array.push("0")
    end
    puts "left_array = #{left_array}"
    puts "right_array = #{right_array}"
    if left_array[0] == right_array[0]
      if left_array[1] == right_array[1]
        if left_array[2] == right_array[2]
          if left_array[3] == right_array[3]
            return 0
          else
            return left_array[3].to_i <=> right_array[3].to_i
          end
        else 
          return left_array[2].to_i <=> right_array[2].to_i
        end
      else
        return left_array[1].to_i <=> right_array[1].to_i
      end
    else
      return left_array[0].to_i <=> right_array[0].to_i
    end
  end
end

filenames = [
  "foo-1.10.2.ext",
  "foo-1.11.ext",
  "foo-1.3.ext",
  "foo-1.50.ext",
  "foo-1.8.7.ext",
  "foo-1.9.3.ext",
  "foo-1.ext",
  "foo-10.1.ext",
  "foo-10.ext",
  "foo-100.ext",
  "foo-2.0.0.ext",
  "foo-2.0.1.ext",
  "foo-2.0.ext",
  "foo-2.007.ext",
  "foo-2.01.ext",
  "foo-2.012b.ext",
  "foo-2.01a.ext",
  "foo-2.0a.ext",
  "foo-13.ext",
  "foo-2.0b.ext",
  "foo-2.1.ext",
  "foo-25.ext",
  "foo-6.ext",
]

puts filenames.version_sort