(Note more precise topic.)
> -----Original Message-----
> From: Aaron Sherman [mailto:[EMAIL PROTECTED]
>
> On Fri, 2004-04-30 at 17:58, Austin Hastings wrote:
>
> > class Session
> > {
> > does ListOfMessages
> > (
> > attribute_base => 'messages',
> > method_base => 'messages',
> > display_color => 'black'
> > );
> >
> > does ListOfMessages
> > (
> > attribute_base => 'errors',
> > method_base => 'errors',
> > display_color => 'red'
> > );
> >
> > ...
> > }
>
> > Can I just do:
> >
> > role ListOfMessages($attribute_base, $method_base,
> $display_color) {...}
>
> I think you want a combination of re-dispatch and delegation:
>
> class Session {
> role EventHandler {
> # The one and only place you define the behavior
> method clear() {...}
> method add() {...}
> method have() {...}
> method get() {...}
> }
> class ErrorHanlder {
> does EventHandler;
> # Probably should do some funky re-dispatch thing
> method clear_errors() { .clear() }
> method add_errors() { .add() }
> method have_errors() { .have() }
> method get_errors() { .get() }
> }
> class MessageHanlder {
> does EventHandler;
> method clear_messages() { .clear() }
> method add_messages() { .add() }
> method have_messages() { .have() }
> method get_messages() { .get() }
> }
> has ErrorHanlder $:errors handles <<clear_errors
> add_errors have_errors get_errors>>;
> has MessageHandler $:messages handles
> <<clear_messages add_messages have_messages get_messages>>;
> }
>
> That should do what you want.
Well, not really:
1- It required a lot of text for little gain.
2- Most of the required text was redundant.
What I want is probably something like this:
role ListOfMessages[$method_base]
{
is Array;
handles (s/_$method_base/_messages/);
method clear_messages() { .clear(); }
method add_message($msg) { .push($msg); }
method have_messages() { return .#; }
# Isn't there a .# property for arrays?
method get_messages() { return $_; }
}
which is close to the same size as the original implementation, but still
doesn't speak to collision of the two lists: messages and arrays. I can move
the data declaration into the class, but this loses encapsulation:
class Session
{
has @:messages
does ListOfMessages�messages�;
has @:errors
does ListOfMessages�errors�;
}
It would be even better, of course, if the role could introspect the
variable name (assuming there is one, which isn't always true) and default
to using that for its method_base.
=Austin
