String#rejoin

gistfile1.rb

# Split a string by regular expression, run the block on each element, then 
# join the pieces back together with the right separators.
#
# Example:
# >> "Internationalization's awesome.".rejoin(/\W/) {|x| x.length > 2 ? "#{x[0]}#{x.length - 2}#{x[-1]}" : x }
# => "I18n's a5e."
class String
  def rejoin(sep, &block)
    separators = self.scan sep
    self.split(sep).map(&block).zip(separators).flatten.compact.join
  end
end