Re: Re: Autovivification and soft refs

Just add a bit of info on top of what Abigail-II said. If you my %stopper, it will stop the autovivification:

use Data::Dumper;
my %stopper;
$x = 'stopper';
exists $x->{'y'}->{'z'};
print Dumper $x;

print Dumper \%stopper;
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Which prints:

$VAR1 = 'stopper';
$VAR1 = {};
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Comment out that my %stopper line, you will see the autovivification:

$VAR1 = 'stopper';
$VAR1 = {
          'y' => {}
        };
[download]

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Re: Autovivification and soft refs by Abigail-II (Bishop) on Jan 22, 2004 at 09:35 UTC
If you my %stopper, it will stop the autovivification: Well, that would be strange. Very, very strange. Do you think that happens because there's an explicite check in perl that says "hmmm, we are doing autovivification of a secondary key in the hash, but the parent hash is a lexical, so let's not do it", or that you've hit a strange bug? Or could it be that autovivification is happening? And you are just giving the wrong argument to Dumper? Try giving `\%{"stopper"}` as argument to Dumper. Abigail	[reply] [d/l]
Re: Re: Re: Autovivification and soft refs by thelenm (Vicar) on Jan 22, 2004 at 05:03 UTC
Now that's interesting. Your post inspired me to dig a little deeper... it looks like the autovivification is still happening, but not on the lexical `%stopper`. Instead the global `%::stopper` is affected. Which makes sense, I suppose, because `%::stopper` is what was being affected in Abigail's original snippet, and with no lexical on scope, `%stopper` (i.e. the symbolic reference) was really referring to `%::stopper`. Very interesting, I certainly learned something. Thanks for pointing that out! `use Data::Dumper; my %stopper; $x = 'stopper'; exists $x->{'y'}->{'z'}; print Dumper $x; print Dumper \%stopper; print Dumper \%::stopper;` [download] -- Mike -- `XML::Simpler does not require XML::Parser or a SAX parser. It does require File::Slurp. -- grantm, perldoc XML::Simpler`	[reply] [d/l] [select]