Hmmm... prototype-based programming?

Something like Self (or NewtonScript), where your objects inherit not from classes but from prototypes (usually one, but it can be extended), and each object is more-or-less a hash (with subrefs for methods), and you search for a value, given the key, starting from the invocant (which is passed to each method call unchanged) up through the proto chain.

$obj1={
  _proto=>$base_obj,
  do_something=>sub{
    print $_[0]->get('string')},
  string=>'object one'};
$obj2={
  _proto=>$obj1,
  change=>sub{
    $_[0]->set('string',$_[1])}};

$obj2->call('do_something');
$obj2->call('set','object two');
$obj2->call('do_something');
$obj1->call('do_something');
__END__
would print:

object one
object two
object one
[download]

This would work since the get walks the proto chain, but set sets thing directly on the invocant.

Of course you can clean up the syntax using AUTOLOAD and tied hashes, but that's just sugar.

In your case, you'll have each buffer as an object, with proto=>$BaseBuffer, and each "mode" will add itself to the proto chain: on reading, the value will be the mode's default, on writing you'll get a "buffer-local" variable.

-- 
        dakkar - Mobilis in mobile