FIRSTKEY this 

This method will be triggered when the user is going to
iterate through the hash, such as via a keys() or each() 
call. 


    sub FIRSTKEY {
carp &whowasi if $DEBUG;
my $self = shift;
my $a = keys %{$self->{LIST}};# reset each() iterator
each %{$self->{LIST}}
    }  

 NEXTKEY this, lastkey 

This method gets triggered during a keys() or each() 
iteration. It has a second argument which is the last key 
that had been accessed. This is useful if you're carrying 
about ordering or calling the iterator from more than one 
sequence, or not really storing things in a hash anywhere. 


For our example, we're using a real hash so we'll do just 
the simple thing, but we'll have to go through the LIST 
field indirectly. 


    sub NEXTKEY  {
carp &whowasi if $DEBUG;
my $self = shift;
return each %{ $self->{LIST} }
    }  
##</code><code>##

package Foo;

sub TIEHASH { bless {}, shift; };
sub FIRSTKEY { wantarray ? print "Array\n" : print "Scalar\n" };
*NEXTKEY = *FIRSTKEY;
sub FETCH { return };

package main;

tie %me, Foo;
() = each %me;
scalar each %me;
__END__
Scalar
Scalar