[REBOL] Re: On mutability and sameness
From: joel:neely:fedex at: 16-Jun-2001 22:21
Hi, again, Ladislav,
Ladislav Mecir wrote:
> a sample thought (you need not take it seriously):
>
But I *always* take you seriously! ;-)
> > MY MODEL:
> >
> > a) All set-path expressions cause something to be mutated.
> > The "something" is identified by the set-path up to the
> > last #"/" and which part of that "something" is identified
> > by what follows the last #"/". Any such "something" is
> > mutable.
>
> A possible POV: once upon a time the time values in Rebol
> behaved like:
>
> a: 12:30 ; == 12:30
> a/hour: 13 ; == 13:30
> a ; == 12:30
>
I don't know if anyone else did, but I reported that behavior
to RT as questionable. In a subsequent release, it was changed.
I conclude that either someone changed his mind, or that the
original behavior was a bug.
> Back then your rule was incorrect. Your rule hasn't changed
> since then and therefore it is still incorrect.
>
Actually, the prior behavior led me to conclude that TIME!
values were immutable, and I stated so at the time (pardon the
pun ;-). Now that that behavior has changed, I conclude that
TIME! values are mutable.
I did not state the simplified "rule" above until *after*
TIME! values became mutable.
-jn-
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joel'dot'neely'at'fedex'dot'com
