accessors.rb

class Person

    class << self
        attr_accessor :personalities

        # Normally we would do this with 'def self.whatever', but because
        # of the class << self idiom above, we're already in the scope of
        # the Person class
        def whatever
            "Hey man"
        end
    end

    # After the end of the class << self clause, we are back into the scope
    # of the Person INSTANCE

    attr_accessor :personality

end

Person.personalities = ['friendly', 'grumpy']

puts Person.personalities.inspect

puts Person.whatever

# This will error out because the accessors for 'personality' were defined for
# INSTANCES of Person, not the class itself
puts Person.personality