The example under the debugger that I gave works only for a two-level hash dereferencing. It has to be adapted for other levels.

I slightly modified the program you made based on my idea so that it takes into account the number of elements in the array of keys, as follows:

#! /bin/perl

use Data::Dumper;

my $hash = {
        'wheels' => {
                'four' => {
                        'car' => {
                                'plain' => {
                                        'sporty' => 'honda',
                                        'retro' => 'volkswagon',
                                        },
                                'fancy' => {
                                        'red' => 'ferrari',
                                        'silver' => 'maserati',
                                        },
                                },
                        'truck' => {
                                'light' => {
                                        'chevy' => 'pickup',
                                        },
                                'utility' => {
                                        'us' => 'mail',
                                        'city' => 'trash',
                                        'muni' => 'power',
                                        'corp' => {
                                                'dom'   => 'dominion p
+ower',
                                                'vap'   => 'virginia p
+ower',
                                                },
                                        },
                                },
                        },
                'one' => 'Unicycle',
                'two' => {
                        'pedals' => 'bicycle',
                        'motorized' => 'motorcycle',
                        },
                'three' => 'tricycle',
                }
            };


##---------------------------
## DEEP REFERENCE
##---------------------------

fetch2($hash, 'wheels');
fetch2($hash, 'wheels', 'four', 'truck');
fetch2($hash, 'wheels', 'four', 'truck', 'utility');
fetch2($hash, 'wheels', 'four', 'truck', 'utility', 'blah');
fetch2($hash, 'wheels', 'four', 'truck', 'utility', 'corp', 'dom');

## Using your suggested technique
sub fetch2 {
        my ($hash, @keys) = @_;
        print "==> Fetching [" . join(', ', @keys) . ']' . "\n";
        my $command_string = 'print Dumper $hash->' . '{shift @keys}' 
+x scalar @keys;
        eval "$command_string";
        }

[download]
And I get the following output, which seems correct to me: 
$ perl  deep.pl
==> Fetching [wheels]
$VAR1 = {
          'three' => 'tricycle',
          'one' => 'Unicycle',
          'two' => {
                     'pedals' => 'bicycle',
                     'motorized' => 'motorcycle'
                   },
          'four' => {
                      'car' => {
                                 'plain' => {
                                              'sporty' => 'honda',
                                              'retro' => 'volkswagon'
                                            },
                                 'fancy' => {
                                              'silver' => 'maserati',
                                              'red' => 'ferrari'
                                            }
                               },
                      'truck' => {
                                   'light' => {
                                                'chevy' => 'pickup'
                                              },
                                   'utility' => {
                                                  'city' => 'trash',
                                                  'muni' => 'power',
                                                  'us' => 'mail',
                                                  'corp' => {
                                                              'dom' =>
+ 'dominion power',
                                                              'vap' =>
+ 'virginia power'
                                                            }
                                                }
                                 }
                    }
        };
==> Fetching [wheels, four, truck]
$VAR1 = {
          'light' => {
                       'chevy' => 'pickup'
                     },
          'utility' => {
                         'city' => 'trash',
                         'muni' => 'power',
                         'us' => 'mail',
                         'corp' => {
                                     'dom' => 'dominion power',
                                     'vap' => 'virginia power'
                                   }
                       }
        };
==> Fetching [wheels, four, truck, utility]
$VAR1 = {
          'city' => 'trash',
          'muni' => 'power',
          'us' => 'mail',
          'corp' => {
                      'dom' => 'dominion power',
                      'vap' => 'virginia power'
                    }
        };
==> Fetching [wheels, four, truck, utility, blah]
$VAR1 = undef;
==> Fetching [wheels, four, truck, utility, corp, dom]
$VAR1 = 'dominion power';

[download]

In reply to Re^3: Return a Deep Hash Reference from Array of Keys by Laurent_R
in thread Return a Deep Hash Reference from Array of Keys by bratwiz

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