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Postings from January 2003
Re: Arrays: is computed
From:
Leopold Toetsch
Date:
January 30, 2003 22:50
Subject:
Re: Arrays: is computed
Message ID:
3E3A1B61.5070702@toetsch.at
Michael Lazzaro wrote:
>
>> gregor@focusresearch.com wrote:
>>
>>> Shouldn't access to 'is computed' arrays be read-only?
> In general, I would hope that 90% of them would be, but it's been stated
> that it won't be a requirement.
If you want such 'is computed' thingy, then tie it or wrap it in your
own - IMHO. Everyone seems to need different things, so the simplest and
by far the safest way is to make this explicit in your code.
> Hmm... real vs. fake undef... a difference between null-PMC and
> PMC-null, autofill with null-PMC, but assigning undef writes PMC-null...
> is that enough to make it work w/out speed penalty? Dan/Leopold?
The array starts filled with zero's. A default value would mean, to fill
each allocated array slot with a PerlUndef PMC (or a specific value
respectively) which is expensive.
On reading a NULL this gets converted to a new PerlUndef on the fly. I
don't see, what more is necessary - and:
my $val = @a[5] or $my_default;
> But making C<undef @a[n]> and C<@a[n] = undef> do very different things,
> that's still scary. Powerful, but scary. People really, really want
> that, huh?
This sould be really the same. But I could imagine to have something
like @a.nullify(5);
> On Thursday, January 30, 2003, at 02:30 PM, Nicholas Clark wrote:
>
>> I think there is a lot of scope for creating tied objects for all of this
>> complex behaviour. Everyone has different ideas about what would be
>> useful,
Yep, exactly.
> Agreed. Very, very agreed. :-) DAMN, I want to start using this NOW.
>
> MikeL
leo