There's no problem with asking follow up questions.

1. Just like

DiveVal(\%hash, map \$_, @elts) = $val;
[download]

it does

$hash{ $elts[0] }{ $elts[1] }...{ $elts[n-1] } = $val;
[download]

If you have data like

foo.bar=val
foo.bar.baz=val
[download]

you'd be better off with pc88mxer's updated code.

2. Keys can be added and removed, not changed. However, combining a removal and an addition is easy.

$hash{$new_key} = delete $hash{$old_key};
[download]

or

$hash{$new_key} = delete $hash{$old_key}
   if exists $hash{$old_key};
[download]