Add chained attr accessors using coffeescript classes

gistfile1.coffee

# utility that allows us to defined chained attr accessors on classes
Function::chain_accessor = (attrs...) ->
  for attr in attrs
    # add the function to the prototype. we wrap the function in a closure
    # to ensure that "attr" keeps its value so we are accessing the right
    # attribute when we call this function later
    @::[attr] = do (attr) ->
      (data) ->
        return @["_#{attr}"] unless data?
        @["_#{attr}"] = data
        return @