Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl-Sensitive Sunglasses
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Whenever a non-existing hash or array element is used in anything but a simple context, it's autovivificated. The *default* is to autovivificate - it's just that the exceptions happen to be the most often used cases, so it's a surprise when perl autovivifies.
#!/usr/bin/perl use strict; use warnings; my %hash; sub X {} my $x; $x = exists $hash{key1}; printf "key1 %sautovivified\n", exists $hash{key1} ? "" : "not "; $x = $hash{key2}; printf "key2 %sautovivified\n", exists $hash{key2} ? "" : "not "; $x = exists $hash{key4}{key3}; printf "key3 %sautovivified\n", exists $hash{key4}{key3} ? "" : "not +"; printf "key4 %sautovivified\n", exists $hash{key4} ? "" : "not "; ($x) = @hash{key5}; printf "key5 %sautovivified\n", exists $hash{key5} ? "" : "not "; ($x) = @hash{"key6", "key7"}; printf "key6 %sautovivified\n", exists $hash{key6} ? "" : "not "; printf "key7 %sautovivified\n", exists $hash{key7} ? "" : "not "; X($hash{key8}); printf "key8 %sautovivified\n", exists $hash{key8} ? "" : "not "; X(@hash{key9}); printf "key9 %sautovivified\n", exists $hash{key9} ? "" : "not "; X(@hash{"keyA","keyB"}); printf "keyA %sautovivified\n", exists $hash{keyA} ? "" : "not "; printf "keyB %sautovivified\n", exists $hash{keyB} ? "" : "not "; __END__ key1 not autovivified key2 not autovivified key3 not autovivified key4 autovivified key5 not autovivified key6 not autovivified key7 not autovivified key8 not autovivified key9 autovivified keyA autovivified keyB autovivified
Perl --((8:>*

In reply to Re^2: Autovivification sucking the life out of me by Perl Mouse
in thread Autovivification sucking the life out of me by shenme

Title:
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?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others examining the Monastery: (3)
    As of 2021-04-17 10:52 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      No recent polls found

      Notices?