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All the Perl that's Practical to Extract and Report

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  • I totally agree with you, I think that it is backwards that it doesn't DWIM. The other comments are just the typical lame gut reaction by people who don't get it comments.
    • I don't think it's a gut reaction, lame or otherwise. The proponents seem to be the ones who haven't thought things through. It's not at all clear what DWIM behavior is in this case. It has to handle nonempty arrays as well:

      my @foo = 1 .. 3;
      $foo[10] = "foo"; # legal
      $foo[-10] = "foo"; # illegal, but what do you expect?
      • In fine tradition with language design flames I am going to point out that dbjerg points out exactly what he expects and I get this, you however do not.

        Therefore I don't see any reason to tell you what I expect, because I expect what dbjerg already said and you didn't get that.
        • I'm sorry, but I see nothing in djberg96's posts that addresses nonempty arrays at all. Both rjbs and jsmith have raised the issue, but neither has received an answer.
          • See, I get what he means, you don't.

            djberg96> In that case, I would expect it to act like a positive
            djberg96> integer, only in reverse. Thus, $array[-3] would result
            djberg96> in an array ("foo",undef,undef).

            Easy eh?
            • I assumed he was talking about starting with an empty array there. I'm talking about when the array already has something in it. Do you really mean to say that after this

              my @foo = 1 .. 3;
              $foo[-4] = 'foo';

              you would expect to lose what had been in the array before and be left with just ('foo', undef, undef, undef)?

      • my @foo = 1 .. 3;
        $foo[10] = "foo"; # legal
        $foo[-10] = "foo"; # illegal, but what do you expect?

        For brevity's sake, let's cut the index down to 5. So, using your example, $foo[5] = "foo" would be:


        So, what would I expect from $foo[-5] = "foo"? I would expect @foo to be:

        # One less undef, because the reverse index starts at -1, not -0.

        • Thanks. So you expect it to move the existing array elements into other places. Is there anyone else out there besides you and sky who would expect that?

          I think the reason that assigning to nonexistent array elements with negative indices doesn't work is that there's no consistent way to do it.

          I can only guess that it seems consistent to you because, from the point of view of someone who only uses negative array indices, the equivalent assignment with a positive index is "moving" array elements. But I don
          • Is there anyone else out there besides you and sky who would expect that?

            Not normally, but in Perl? Yes, I would.

            Here is why...

            Suppose you have an array, of any size. When you hit it with an assignment using an index who's absolute value is larger than the array size... it will, basically perform a "push" onto the end of the array (the right side) until the array size = the absolute value of the index if the index is positive.

            Then it will do the assignment.

            So, it is a two step process for positive in