barf = "hello" puts barf barf.upcase! puts barf
ruby ruby-strings.rb hello HELLO
Pretty boring, huh? Well one of the nice things about Ruby is that you can do stuff like this:
class String def goodbye puts "Goodbye" end end barf = "hello" puts barf barf.upcase! puts barf barf.goodbye
Yes, very cool. What happened here was the function goodbye was added to the string class, so that every string object has access to it. Very very cool.
Related: Introduction to Ruby Modules