[REBOL] Re: Core 2.5.5 Beta Versions
From: lmecir:mbox:vol:cz at: 23-Feb-2003 19:48
Hi all,
I would like to welcome Elan too.
<Gabriele wrote:>
> (Anyway, the proposal I and Romano sent to feedback asked
> for a different solution to the problem; I still think it would be
> better.)
I don't know your proposal, but I suspect, that its feasibility was
questionable (for the current interpreter implementation).
<Joel wrote:>
> > How to resolve this situation of confusion between out-of-range
> > series and tail series?
> >
> I suggest that the following behavior for series values is simple,
> and also makes sense (not always the same! ;-)
>
> - INDEX? should *always* return the "position" of the series,
> regardless of the number of values in the underlying sequence.
Count my vote for this too. I call it a REAL-INDEX? as opposed to any
adjusted indices. My reasons for it are:
1) Compatibility: this behaviour is the most compatible, because if we had
such a function, it would be easy to define an PRE-255-INDEX? as follows:
PRE-255-INDEX?: func [
[catch]
s [series!]
] [
either real-index? :s <= (real-index? tail :s) [
real-index? :s
] [
throw make error! "Out of range"
]
]
as well as INDEX?-255
INDEX?-255: func [
[catch]
s [series!]
] [
either real-index? :s <= (real-index? tail :s) [
real-index? :s
] [
throw make error! "Out of range"
]
]
, while neither of these can be used alone to define REAL-INDEX?.
2) Symmetry: REAL-INDEX? is much more symmetrical, than any other
implementation proposed (its behaviour doesn't depend on some factors, that
are essential for other proposed indices).
