Hi Me here again. Can't find the ref to 'auto vivification'. Still trying to find out more about it. Can you give me a brief run down.

I been using the set() function which works well. The next step is to add items into the tree. To do this I am using the same idea of passing a path. The question arises when passing a new path to a empty tree. i.e

set($ref_to_hash,1,(a c b d))

# set($hoh,$val, @path): ... by ariels

sub set {
  my $hoh = shift;
  my $val = shift;
  my $last = pop @_;
  $hoh = $hoh->{$_} for (@_);
  $hoh->{$last} = $val
}
[download]

the set function works if the 'a c b ' already exists. If it doesn't then we simply create a hash in space somewhere ( i think ). What I need is to dynamically create nodes which do no exist. I have done this by using a temporary hash to add the new item in and then link it back into the tree.

#create first node
$hr=\%I;
$hr->{'one'}=1;

#create tmp node and link back in
$new=\%tmp;
$new->{'two'}=1;
$hr->{'one'}=$new;
[download]

Seems to work ok but I reckon you'll have a better way Thanks again wert