As for speed, you're completely and utterly wrong. Symbolic references ARE hashes. The hash being used is the symbol table. It actually uses MORE memory because of how the symbol table is implemented.

Did you actually try my suggestions? Or, did you just read them and go "I don't get it."?

Did you actually try my suggestions? Or, did you just read them and go "I don't get it."?

Yes, I tried your suggestions. I'm really interested in knowing how you would solve the problem, but with your indications I didn't get it:

Remove the no strict 'refs'; in both subroutines and try the following: ...

my $root = {};
_create_node ($root,"pp1","first");
_create_node ($root->{pp1},"ppp1","second");
_create_node ($root->{ppp1},"pppp1","third");
_create_node ($root->{pppp1},"ppppp1","root");

my $infos = _go_through('p1');
#my $infos = _go_through($root); # doesn't work either

print Dumper $infos;

sub _create_node
  {
#    no strict 'refs';
    my ($node,$parent,$node_info) = @_;
    @{$node}{qw/parent info/} = ($parent,$node_info);
  }

sub _go_through
  {
    my ($node) = @_;
    return "" unless defined ${$node}{"info"};
    my @info_nodes;
    while (${$node}{"info"} ne "root"){
      push @info_nodes, (${$node}{"info"});
      $node = ${$node}{"parent"};  ## Line 33
    }
    return \@info_nodes;
  }
[download]

This doesn't work:

Can't use string ("pp1") as a HASH ref while "strict refs" in use at ... line 33

Obviously, I'm missing something, that is why I asked

citromatik

Oh. I see the problem and why I didn't see it before. Your problem is that you're mixing data structures. Try the following version of _create_node and _go_through:

_create_node ('p1',"pp1","first");
_create_node ('pp1',"ppp1","second");
_create_node ('ppp1',"pppp1","third");
_create_node ('pppp1',"ppppp1","root");

my $infos = _go_through('p1');
print Dumper $infos;

{
    my %nodes;
    sub _create_node {
        my ($node_id,$parent,$node_info) = @_;
        @{$nodes{$node_id}}{qw/parent info/} = ($parent,$node_info);
    }

    sub _go_through {
        my ($node_id) = @_;
        return "" unless defined ${$nodes{$node_id}}{"info"};
        my @info_nodes;
        while (${$nodes{$node_id}}{"info"} ne "root"){
            push @info_nodes, (${$nodes{$node_id}}{"info"});
            $node_id = ${$nodes{$node_id}}{"parent"};  ## Line 33
        }
        return \@info_nodes;
    }
}
[download]

I actually tested this code. :-)

---

My criteria for good software:

1. Does it work?
2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

You need to adjust your syntax, try:

$node = $node->{"parent"};  ## Line 33
[download]

Update: this is incorrect, please ignore.

I think you should show us an example of those lists and what do you need to do with them and I bet we can suggest a solution that will use significantly less memory and will be quicker than your symbolic references. Do not use symbolic references! Ever.