Beefy Boxes and Bandwidth Generously Provided by pair Networks
Problems? Is your data what you think it is?

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

Tell you what: It's perplexing to me the other way around!

Until 2 days ago I thought something like
if ($foo{'BAR'}) ...
would already vivify that hash entry.

But then I learned in the Chatter Box that it doesn't in perl 5.8 (or maybe a bit earlier).

And now I did a test. Compare the output

use Data::Dumper; %foo=(BAZ=>1); print Dumper \%foo if $foo{BAR} || 1; print Dumper \%foo if @foo{BAR,BAZ} || 1;

$VAR1 = {
          'BAZ' => 1
$VAR1 = {
          'BAZ' => 1

use Data::Dumper; %foo=(BAZ=>1); print Dumper \%foo if call($foo{BAR}); print Dumper \%foo if call(@foo{BAR,BAZ}); sub call { return 1 }

$VAR1 = {
          'BAZ' => 1
$VAR1 = {
          'BAR' => undef,
          'BAZ' => 1

So it's really the fact that the slice is used in a subroutine call. When you replace call with print, autovivification does not happen

So now I ask myself: Is there a bug and you are certified bugfinder!? ;-)


In reply to Re^3: Autovivification sucking the life out of me by Skeeve
in thread Autovivification sucking the life out of me by shenme

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others studying the Monastery: (3)
    As of 2021-04-11 13:24 GMT
    Find Nodes?
      Voting Booth?

      No recent polls found