use strict;
use warnings;

sub get {
   my $ref = shift(@_);
   my $key = shift(@_);
   my $val;

   for (;;) {
      last unless UNIVERSAL::isa($ref, 'HASH');
      
      $val = $ref->{$key}
         if exists $ref->{$key};

      last unless @_;
      my $branch = shift(@_);
      $ref = $ref->{$branch};
   }

   return $val;
}

my $data = {
   Colour  => 'blue',
   Entries => {
      Flowers => {
         Dahlia => { Smell  => 'nice' },
         Rose   => { Colour => 'red'  },
      },
   },
};

print
   get($data, 'Colour', qw( Entries Flowers Rose   )), $/,  # red
   get($data, 'Colour', qw( Entries Flowers Dahlia )), $/;  # blue

##</code><code>##

print
   $data->get('Colour', qw( Entries Flowers Rose   )), $/,  # red
   $data->get('Colour', qw( Entries Flowers Dahlia )), $/;  # blue