--- const_missing(name)       ruby 1.8 feature

    Ƥʤ򻲾ȤȤ Ruby Υ᥽åɤƤ
    ޤȤ̾ Symbol Ϥޤ

    ǥեȤǤϤΥ᥽åɤ㳰 NameError ȯޤ

        class Foo
          def Foo.const_missing(id)
            warn "undefined constant #{id.inspect}"
          end

          Bar
        end
        Foo::Bar

        # => undefined constant :Bar
             undefined constant :Bar

