> > On Sat, Jul 05, 2003 at 09:51:29AM -0600, Luke Palmer wrote: > > > > > Actually, you can't reference a slice! Where the heck does the > > > reference point? I would probably do: > > > > Of course not. I presume it points to something non-existent just like > > a substring reference would in perl5 :-) > > > > $ perl -le '$a = "pie contest"; $b = \substr $a, 1, 9; $$b = "arro"; print $a' > > parrot > > I don't think you're supposed to do that: > > % perl -le '$a = "foobar'; $b = \substr $a,2,3; $a .= "jibby"; $$b = "OBA"; > print $a' > foobarjibby > > Because it copies the buffer to resize, and $b points back into the old buffer...
Forget I said that. I put $b = "OBA" in my command line instead of $$b. It works. Luke > But a slice can be used as an lvalue, so I guess it would be valid to > reference it (just like substr *should* be). > > The tricky stuff comes in in cases like: > > my @a = (1,2,3,4,5); > my $sref = [EMAIL PROTECTED]; > shift @a; > @$sref = (4,3,2); > @a # ? (4,3,2,5) or (2,4,3,2) ? > > Those are just semantics to be nailed down, but it's tricky > nonetheless... oh and let's not forget multidimensional slices. > > This really comes down to an issue that I've been biting my > fingernails about for some time: iterators. There are two mutually > exclusive kinds of iterator semantics: list and array. In the above > example, (4,3,2,5) would be list semantics; (2,4,3,2) would be array. > And both of them are correct (or wrong) in certain applications. > > For implementation reasons, I'm not sure it's possible to have both > kinds of iterator pointing into the same kind of array. Perhaps we > need a List class for an array which doesn't support indexing... but > then it doesn't really deserve the @ medal does it? > > Hmm... > > Luke > > > Nicholas Clark
