How can I check if a key exists in a deep Perl hash?

Question

If I understand correctly, calling if (exists $ref->{A}->{B}->{$key}) { ... } will spring into existence $ref->{A} and $ref->

Answer 1

Take a look at Data::Diver. E.g.:

use Data::Diver qw(Dive);

my $ref = { A => { foo => "bar" } };
my $value1 = Dive($ref, qw(A B), $key);
my $value2 = Dive($ref, qw(A foo));