>>159
undef でどうよ？
----------------------------------------
class C1
def foo
puts "OK"
end
end

class C2 < C1
undef foo
end

C1.new.foo #=> "OK"
C2.new.foo #=> undefined method `foo'
----------------------------------------
リファレンスだと
http://ruby-lang.org/ja/man/index.cgi?cmd=view;name=%A5%AF%A5%E9%A5%B9%A1%BF%A5%E1%A5%BD%A5%C3%A5%C9%A4%CE%C4%EA%B5%C1#undef