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;
Output:
$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 }
Output:
$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!? ;-)
s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e
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