From: Robert Klemme <shortcutter@...>
Date: 2013-03-21T02:50:47+09:00
Subject: Re: Ruby tainting on primitives

On Wed, Mar 20, 2013 at 6:35 PM, Nicolas V. <lists@ruby-forum.com> wrote:
> I'd like to use tainting to keep track of some data moving around.
>
> The fact that numbers are immutable isn't really relevant. The fact that
> they're immutable doesn't necessitate they be singletons.

But they are singletons.  That is a fact.

> I realize that Fixnums are implemented as singletons as an optimization,
> but that's an implementation detail that shouldn't change the behavior
> of tainting.

It doesn't.  But tainting is associated with the instance.  Hence if
you taint 0 all empty Arrays and Hashes will return a tainted 0 as
result of #size.  That doesn't make sense at all.  It also won't help
you with tracking "data moving around".

> Ruby abstracts the implementation of Fixnums in other ways.
> For example, running `123.class` suggests that 123 is an instance of
> Fixnum. I don't understand why tainting should be different.

See above.

Cheers

robert



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