#!/usr/bin/perl

use Data::Dumper;

my $hash = {
	a => { ab => { ac => 'fred' }, abb => 'barney' },
	b => 'betty',
	c => { cb => 'dino' },
	};

my $r = $hash;

my @k = qw( a ab );

print Dumper( $hash );

$r = $r->{$_} foreach @k;

$r->{ 'ac' } = 'Mr. Slate';

print Dumper( $hash );