2012/11/5 mame (Yusuke Endoh) <mame / tsg.ne.jp>:
>
> Issue #7216 has been updated by mame (Yusuke Endoh).

> Akr-san, what do you think?

It may be good idea.

The root problem is that Liskov substitution principle is violated
between Object and TrueClass.
(Object is clonable but its subclass, TrueClass, is not.)

So, such unprincipled classes may have responsibility to
undefine/unimplement methods which don't work.

I feel it's better to ask matz.
-- 
Tanaka Akira