From: Aredridel <aredridel@...>
Date: 2004-09-04T03:04:13+09:00
Subject: Re: Not just $SAFE, but damn $SAFE

On Fri, 2004-09-03 at 17:08 +0900, ts wrote:
> >>>>> "A" == Aredridel  <aredridel@nbtsc.org> writes:
> 
> A> Class === obj # Bad, because you can define an evil subclass.
> 
>  This is not a problem.
> 
>  1) if you use `case', you can trust the result (i.e. an object can't "lie")

Except that by using case, I can have an EvilString < String, for which
that returns true.

>  2) you know that some methods are safe. For example, if you have a String
>     or an Exception use String.new(obj). If you have an Integer or a
>     Bignum, use Integer(String.new(obj.to_s)). If you have a Time object
>     use Time.at(obj), etc
> 
>     Now, if you have a container (Array, Hash, ...) just create a new
>     container and store it only "safe" objects.

Yup. That's similar to what we're doing. The problem lies in to_s, in
that our eventual goal is to output text. Any deep data structure is
harder to deal with.

Ari