Recursively printing data structures in Perl

Question

I am currently learning Perl. I have Perl hash that contains references to hashes and arrays. The hashes and arrays may in turn contain references to other hashes/arrays.

I wrote a subroutine to parse the hash recursively and print them with proper indentation. Though the routine works as expected, my instructor was not convinced about the readability and elegance of the below code.

I would really appreciate to get the views of Perl experts here on possible optimization of the below code.

Here is my complete code snippet..

# Array of Arrays
$ref_to_AoA = [
     [ "fred", "barney" ],
     [ "george", "jane", "elroy" ],
     [ "homer", "marge", "bart" ],
];


#Array of Hashes
$ref_to_AoH = [ 
{
   husband  => "barney",
   wife     => "betty",
   son      => "bamm bamm",
},
{
   husband => "george",
   wife    => "jane",
   son     => "elroy",
},
];

# Hash of Hashes
$ref_to_HoH = { 
    flintstones => {
        husband   => "fred",
        pal       => "barney",
    },
    jetsons => {
       husband   => "george",
       wife      => "jane",
       "his boy" => "elroy",  # Key quotes needed.
    },
    simpsons => {
       husband   => "homer",
       wife      => "marge",
       kid       => "bart",
    },
};

# Hash which contains references to arrays and hashes
$finalHash = {
   'arrayofArrays' => $ref_to_AoA,
   'arrayofHash' => $ref_to_AoH,
   'hashofHash' => $ref_to_HoH,
};

$string = str($finalHash); 
print "$string\n";

#------------------------------------------------------------------
sub str {
    my $hash = shift;
    my ($space, $newline, $delimiter) = @_;
    $space = "" unless (defined $space);
    $newline = "\n\n\n" unless (defined $newline);
    $delimiter = "\n--------------------------------------------" unless (defined $delimiter);
    my $str = "";

    for (sort keys %{$hash}) {
        my $value = $hash->{$_};
        $str .= "$newline$space$_ == $value$delimiter";
        $str .= recurseErrors($value,$space);
    }
    $str;
}

#------------------------------------------------------------------
sub recurseErrors {
    my $str;
    my ($value,$space) = @_;
    my $ref = ref $value;

    if ($ref eq 'ARRAY') {
        my $i = 0;
        my $isEmpty = 1;
        my @array = @$value;
        $space .= "\t";
        for my $a (@array) {
            if (defined $a) {
                $isEmpty = 0;
                $str .= "\n$space$_\[$i\] :";
                $str .= recurseErrors($a,$space);
            }
            $i++;
        }
        $str .= "= { }" if ($isEmpty);

    } elsif ($ref eq 'HASH') {
        $space .= "\t";
        for my $k (sort keys %$value) {
            if ( ( ref($value->{$k}) eq 'HASH') || (ref $value->{$k} eq 'ARRAY') ) {
                my $val = $value->{$k};
                $str .= "\n\n$space$k == ";
                $str .= "$val";
            }
            else {
                $str .= "\n$space$k == ";
            }
            $str .= recurseErrors($value->{$k},$space);
      }

      # we have reached a scalar (leaf)
    } elsif ($ref eq '') {
        $str .= "$value";
    }
$str
}
#------------------------------------------------------------------

Output:

arrayofArrays == ARRAY(0x9d9baf8)
--------------------------------------------
    arrayofArrays[0] :
        arrayofArrays[0] :fred
        arrayofArrays[1] :barney
    arrayofArrays[1] :
        arrayofArrays[0] :george
        arrayofArrays[1] :jane
        arrayofArrays[2] :elroy
    arrayofArrays[2] :
        arrayofArrays[0] :homer
        arrayofArrays[1] :marge
        arrayofArrays[2] :bart


arrayofHash == ARRAY(0x9d9bba8)
--------------------------------------------
    arrayofHash[0] :
        husband == barney
        son == bamm bamm
        wife == betty
    arrayofHash[1] :
        husband == george
        son == elroy
        wife == jane


hashofHash == HASH(0x9da45f8)
--------------------------------------------

    flintstones == HASH(0x9d9bb48)
        husband == fred
        pal == barney

    jetsons == HASH(0x9d9bbf8)
        his boy == elroy
        husband == george
        wife == jane

    simpsons == HASH(0x9d9bc48)
        husband == homer
        kid == bart
        wife == marge

Answer 1

maybe Data::Dumper is what you want:

use Data::Dumper;

$str = Dumper($foo);
print($str);

Answer 2

My guess is that he doesn't like that you

1. expect a hash in the str function.
2. call the same function to print arrays as hashes, despite that there appears to be no common function between them.
3. allow various ways to call str, but it never figures into the final result.
4. allow configurable space to be passed in to the root function, but have a tab hardcoded in the recursive function.
5. omit undefined values that actually hold a place in the arrays

Those are issues that I can see, pretty quickly.