From: "Peña, Botp" <botp@...>
Date: 2008-11-17T17:12:43+09:00
Subject: Re: How can I overload a method in Ruby

From: Peña, Botp [mailto:botp@delmonte-phil.com] 
# def build directory=nil
#   cd directory unless directory.nil?
#   make
# end


or if you do not like the if/unless part,

def build directory="."
  cd directory
  make
end