Perhaps something like: 

use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);
use Test::More qw(no_plan);

sub deref(@)
 {my $h = shift;
  for(@_)
   {return undef unless $h and ref($h) eq __PACKAGE__ and $h->can($_);
    $h = $h->$_;
   }
  $h
 }

my $h = bless {a=>bless{a=>bless{a=>bless{a=>1, b=>2}}}};

sub aaa() {$_[0]->{a}}
sub bbb() {$_[0]->{b}}

ok !defined($h->deref(qw(bbb bbb bbb bbb)));
ok 1 == $h->deref(qw(aaa aaa aaa aaa));
ok 2 == $h->deref(qw(aaa aaa aaa bbb));

[download]

Produces

ok 1
ok 2
ok 3
1..3

In reply to Re: undef is undef by philiprbrenan
in thread undef is undef by jozef

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