Robert Feldt wrote:

> How "final" is a call to undef_method? Is there any way to get the
> method back, ie. hook it up to the class again?
> 
> [...]
> etc would give a possibility for a kind of simple, fine-grained
> "sandboxing"? (I'm not implying you should do this instead of
> tainting/SAFE-levels etc, just exploring possibilities)

_why is using this already with great success for his TryRuby sandbox. 
I'm not sure if there is ways around it, but it seems quite unlikely.

But you will definitely have to make sure that there is no way of 
loading C extensions. It would be possible to get back the original 
functions that way and do even worse.

-- 
http://flgr.0x42.net/