From: Nikolai Weibull <now@...>
Date: 2013-03-24T17:58:34+09:00
Subject: [ruby-core:53689] Re: [ruby-core:53685] Re: [ruby-core:53680] Re: [ruby-core:53679] Why doesn’t String#+ return an untrusted result if self or other is untrusted?

On Sat, Mar 23, 2013 at 10:42 PM, Nikolai Weibull <now@bitwi.se> wrote:
> On Sat, Mar 23, 2013 at 8:30 PM, KOSAKI Motohiro
> <kosaki.motohiro@gmail.com> wrote:
>> On Sat, Mar 23, 2013 at 2:45 PM, Nikolai Weibull <now@bitwi.se> wrote:

>>> Why doesn���t String#+ return an untrusted result if self or other is untrusted?

>> IIUC, untrusted mean an object was created from untrusted code (i.e. $SAFE >=3).

> OK, so the reasoning then is that since String#+ creates a result that
> contains data from outside of the receiver, untrust isn���t inherited,
> whereas with String#slice and String#downcase the whole result comes
> from an untrusted source and thus untrust is inherited.

(This explanation isn���t consistent with String#center, String#ljust,
and String#rjust, as their results inherit untrust from the padding
argument, so there must be something deeper going on here.)