just recently I got bitten by trying to nest two while (each ) on the same hash, because the iteration-pointer is tied to the hash

If you do not change the hash in the loop, you can use your own iterator like that:

sub hash_iterator {
  my %h = @_;
  return sub {
    each %h;
  }
} # make_iterator

my %test = (k1 => 'v1',
            k2 => 'v2',
            k3 => 'v3',
           'k-last' => 'v-last');

my $it1 = hash_iterator(%test);
my $it2 = hash_iterator(%test);
while(<>){
  print join ':',($it1->())[0,1];
  print ';',join ':',($it2->())[0,1];
  print ' - ',join ':',($it2->())[0,1];
  print "\n";
}
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