It's worth noting that in Ruby the difference between attr_reader and attr_writer is not the same as read only and write only. You can write to something set wi

It's worth noting that in Ruby the difference between attr_reader and attr_writer is not the same as read only and write only. You can write to something set with attr_reader. All attr_writer does is allow complete reassignment of that particular instance variable. This is pretty trivial so bear with me... If you have something that looks like this... class Person attr_reader :children def initialize @children = [] end end You can then do this... x = Person.new x << "Bobby" You will have then altered the value of @children without completely reassigning it.