gistfile1.txt

def read_only_struct(*attrs)
  c = Class.new
  eval_me = <<-CLASS_EVAL_OH_NOES
    def initialize(#{attrs.map { |sym| sym.to_s }.join(', ')})
      #{attrs.map { |attr| "@#{attr} = #{attr}" }.join("\n")}
    end
    
    attr_reader #{attrs.map { |sym| ":#{sym.to_s}" }.join(', ')}
  CLASS_EVAL_OH_NOES
  c.class_eval eval_me
  c
end

Foo = read_only_struct :bar
f = Foo.new 'BAR'
puts "Getter says: #{f.bar}"
puts "Setter should raise an exception:"
f.bar = 'BAZ'