gistfile1.rb

# YARR!

class Event
  def self.[](*attributes)
    c = Class.new(Event)

    unless attributes.empty?
      attributes.each do |attribute|
        c.send(:attr_accessor, attribute)
      end

      c.class_eval <<-END
        def initialize(#{attributes.join(", ")})
          #{attributes.map { |attr| "@#{attr}=#{attr}" }.join(";") }
        end
      END
    end

    c
  end
end

class Test < Event[:this, :that]; end
a = Test.new(3, 4)
a.this = 5
p a.this
p a.that