> On Fri, 22 Sep 2000 08:58:10 +1100, Jeremy Howard wrote:
>
> >Bart Lateur wrote:
> >> Hmm... the problem is, I think, that array references and ordinary
> >> scalars are both scalars.
> >>
> >That's true, but they're scalars with different interfaces. In particular,
> >an array ref can be dereferenced and provides an array in doing so. If an
> >index can do this, then it's a multidimensional index.
>
> That worries me. I'd like to avoid to repeat the fiasco of having the
> same code have different kinds of behavious, depending on the contents
> of a variable, as we have with symbolic references versus anonymous
> arrays/hashes.
>
> What will this return?
>
> $ary[$index]
>
> It looks like a plain and simple array item, but what if $index is an
> array ref?
Then it returns a plain and simple array item from a multidimensional
array.
The main problem I see are these:
@array = ([1,2],[3,4]); # 2-dimensional array, using LOL syntax
print $array[[1,1]]; # prints 4, OK
print $array[1]; # prints ?????
print $array[[1,1,1]]; # prints ?????
print $array[[1]]; # prints ?????
According to RFC 204, $array[1] should return [3,4], $array[[1]] should
return (3,4), and $array[[1,1,1]] should cause a runtime error.
Interestingly enough, my original version of RFC204 had all three of
the "questionable" print statements be runtime errors -- I don't like
LOL-semantics for multidimensional arrays. Somehow, it got changed
when being passed from me through Jerry to the RFC Librarian. I didn't
bother to reread it after it got posted -- I knew what it said -- so I
didn't notice the change.
If anyone is interested, I'll post my original .pod I wrote...
>
>
> >> What would be the difference between
> >>
> >> $a[2]
> >>
> >> and
> >>
> >> $a[[2]]
> >>
> >> anyway? Aren't these just the same?
> >>
> >Nearly! From the RFC:
> >
> ><quote>
> >When a listref is used to index a list of lists, the returned list reference
> >is automatically dereferenced:
> >
> > my @array( [0,1], [1,2]);
> > my @a = @array[[0]]; # Returns (0,1), _not_ [0,1]
> ></quote>
That's part of what I didn't write in "my" RFC.
I especially don't like the line
$array[[1,2]] = (1,2,3,4); # Sets the line at (1,2) to (1,2,3,4)
Huh? That's a scalar on the right, a list on the left? Should that
set $array[[1,2]] to 4?
That'll teach me to proofread what "I" say....
>
> Puh. I'd prefer
>
> my @a = @$array[0];
>
> which is shorter anyway. ;-) Currently, this does the wrong thing,
> and I think that maybe the prefix precedence should be fixed so that
>
> @$ary[0]
>
> is the same as
>
> @{$ary[0]}
>
> Or doe people find it intuitive that this returns a slice of an array
> pointed to by $ary?
I'd find
my @a = @array[0;];
to be nicer -- no references visible, unambiguous, same number of
characters as @$array[0], and symmetrical with
my @b = @array[;0];
for a different dimension. It isn't easy to do that with LOL notation.
> You are right in that. You cannot get a hash slice of a Perl4 style
> "multidimensional" hash. A major stumbling block.
A fatal one, in my opinion.
>
> --
> Bart.
--
Buddha Buck [EMAIL PROTECTED]
"Just as the strength of the Internet is chaos, so the strength of our
liberty depends upon the chaos and cacophony of the unfettered speech
the First Amendment protects." -- A.L.A. v. U.S. Dept. of Justice
