Re: I just want to understand why ...

[Anonymous Monk]

in reply to Why does testing for the existence of hash keys create the keys ?

From the other day see Re: How do you check if a key exists without creating it ?

no autovivification;

if( exists $foo->{bar}{anything}{you}{want} ){
}

Or

use Data::Diver 'Dive';

if( my $want = Dive( $foo, qw/ bar anything you want / ) ){
...
}

[Anonymous Monk]

And then there's the third way which requires some extra typing, but is fine for two-level or three-level hashes:

my $r = $hashref; # better to use a short variable name here
if($r->{a} and $r->{a}->{b} and exists $r->{a}->{b}->{c}) 
{
# Do something
}

[Athanasius]

No autovivification.

Huh?

18:58 >perl -w -Mstrict -MData::Dumper -E "my $foo; say Dumper($foo); 
+if (exists $foo->{bar}{anything}{you}{want} ) { say 'hi' } say Dumper
+($foo);"
$VAR1 = undef;

$VAR1 = {
          'bar' => {
                     'anything' => {
                                     'you' => {}
                                   }
                   }
        };


19:00 >

Looks like 3 levels of autovivification to me.

???

Update: See below.

[choroba]

And where is no autovivification; in your code?

[Athanasius]

Oh, OK, I see it now. In the post by Anonymous Monk, “no autovivification” isn’t formatted as code, so I took it as a comment, didn’t realise it is part of the script! Sorry for the noise. (But, I’ve learned something useful. :-) )