A small class for generating and validating 10's, the 10 digit codes that are found on many book-ish products sold before 2005.
Yes there are man other ISBN gems out there. I wanted one that has a similar API to my other identifier related gems (ean13, abn, san, upc, etc) to reduce the number of APIs I have to remember.
gem install isbn10
ISBN10.new("0140449043").valid?
=> true
ISBN10.valid?("0140449043")
=> true
ISBN10.valid?("0140449042")
=> false
ISBN10.complete("014044904")
=> "0140449043"
ISBN10.new("0140449043").to_ean
=> "9780140449044"
Source code is publicly available @ http://github.com/yob/isbn10. Patches welcome, preferably via a git repo I can pull from.