Last n Characters of a Ruby String

Almost without fail people come to me after using Ruby for a while and ask if there is any easy way to get the last n characters of a string. The easiest way to do it without extending classes is:

str = 'This is a test'
srt[-4,4] # => 'test'

However if you are willing to mixin a nice little method you will forevermore have rapid access to the last characters of a string.

module LastN
  def last(n)
    self[-n,n]
  end
end

class String
  include LastN
end

'This is a test'.last(4) # => 'test'

Enjoy!