I decided to join Ruby Quiz for the first time ever – I am realizing that I am extremely late to jump on the RQ bandwagon – but hey, is still better later than never. I have chosen a funny moment though: it’s a quiz everyone was excited about, but almost nobody solved (2 solutions so far except mine, which is maybe the lowest number of solvers ever). So here’s the quiz:

Your task is to write a units converter script. The input to the
script must be three arguments: the quantity, the source units, and
the destination units. The first example above would be run like this:

    $ ruby convert.rb 50 miles kilometers

Or, using abbreviations:

    $ ruby convert.rb 50 mi km

Support as many units and categories of units (i.e. volume, length,
weight, etc.) as you can, along with appropriate abbreviations for
each unit.

and my solution:

require 'rubygems'
require 'cgi'
require 'scrubyt'

begin
google_converter = Scrubyt::Extractor.define do
 fetch "http://www.google.com/search?q=#{CGI::escape(ARGV[0])}+#{CGI::escape(ARGV[1])}+to+#{CGI::escape(ARGV[2])}"

 google_result "//td[@dir='ltr']" do
   final_result(/= (.+) /)
 end
end
 puts google_converter.to_hash[0][:final_result]
rescue
 puts "Sorry, even *google* can't translate that!"
end

Examples:

ex:
ruby converter.rb 10 "meter per second" "mile per hour"
22.3693629

ruby converter.rb 10 USD EUR
7.91201836

ruby converter.rb 7 "ruby gems" "python eggs"
Sorry, even *google* can't translate that!

The biggest downside of the proposed solution is that you need to be on-line. However, nowadays, when this is almost the norm, the advantages outweigh this in my opinion:

• Support for a lot of conversions (I doubt anyone can offer a much richer database of units than google) including their abbreviations
• Up-to-date conversions: for example currency conversion
• Very robust error handling – outsourced to google! Hard to beat that…