Yes you did do something with it. In order to check whether exists $foo{bar}{baz}, obviously, $foo{bar} must be a hash reference. Perl DWIMs (most of the time) by creating an empty hashref on multilevel lookup attempts, but sometimes, like in your case, that is undesired. What you have to do is clunky: check every level of the hierarchy yourself. Something like 
my $cursor = \%foo;
for(qw(foo bar)) {
    undef $cursor, last unless exists $cursor->{$_};
    $cursor = $cursor->{$_};
}

print "exists\n" if $cursor;

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You want to put this in a function like 
sub exists_novivify {
    my $cursor = shift;
    for(@_) {
        undef $cursor, last
            unless exists $cursor->{$_};
        $cursor = $cursor->{$_};
    }
    $cursor;
}

print "exists\n" if exists_novivify \%foo, qw(bar baz);

[download]
Update: removed duplicate exists. Thanks BrowserUk.

Makeshifts last the longest.

In reply to Re: Autovivification with hash of hashes by Aristotle
in thread Autovivification with hash of hashes by Mr_Person

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