--- Damian Conway <[EMAIL PROTECTED]> wrote: > Austin Hastings wrote: > > --- Austin Hastings <[EMAIL PROTECTED]> wrote: > > > > > >>No, undef. OTOH, deleting @a[1] would reset it to default. > > > > > > Ere someone flames my for using a hash keyword in an array context: > > > > s/deleting/absquatulating (e.g., via pop, shift, or splice)/ > > Unfortunately, I don't think we can base defaultitude on the > (non)existence of > an array element. You end up with some rather nasty > action-at-a-distance. > > Consider: > > my @a is default(666); > > print @a[2]; # prints 666 > > @[4] = 1; > > print @a[2]; # now prints undef :-( > > I think of C<is default> as specifying a mapping from an implicit or > explicit > C<undef> to something else. >
I don't understand your example. Can you explain it again, using words of less than one syllable? What's @[4]? Why does it (even if it's a typo from @a[4]) cause @a[2] to become defined? (Small != dense) If it does become defined, why doesn't it get the default value -- no-one explicitly told it to be undef? > I'm not compelled by the counter-argument that this makes it > impossible to store an C<undef> in an array with a default. > Because the whole point of an array having a default is to > prevent those nasty out-of-range C<undef>s from > popping up in the first place. The point of having a default is to replace those undefs with something else. To prevent them from appearing would require rewriting ones code in such a way that extraordinary arrefs didn't happen. But given that I can replace undef with 'fednu' in these cases, I'd now like to reduce/reuse/recycle my undefs back as meaningful values -- they're not reserved for the special case of LOCALE="noaquistan" any more. > And thinking of defaults as mappings leads me to conclude that it's > entirely reasonable to allow sub refs as default specifiers, as a > means of > creating computed arrays. But I'd expect that the property name is > different > in that case (probably C<is computed>), so as to distinguish: [[ code elided ]] Yeah, that too. I like "is computed". =Austin
