Hmmnn...I don't think so. As far as I can tell, he's talking about
adding more types to a future MINA release. That would mean adding a
method to each new type -- hardly a high cost given the return. If
you want to make it possible for users to add types, you could simply
have an "visitGenericType" method that would be no worse than the
current situation, but it doesn't seem like users adding their own
types would ever be a common use case.
-Adam
On Feb 14, 2008 8:53 AM, David M. Lloyd <[EMAIL PROTECTED]> wrote:
> I believe that Trustin's point is that the visitor pattern is only
> effective if you know all the visitable types ahead of time. It's quite
> difficult for a user to wedge in their own type after the fact - they
> would have to modify the visitor interface for each new transport type
> they add.
>
> - DML
>
>
> Adam Fisk wrote:
> > I actually think that's exactly why the visitor pattern is nice -- the
> > more transports you have, the better it gets because you can elegantly
> > deal with the additional types rather than resorting to instansofs.
> > The double-dispatch method calling is also a bigger performance boost
> > the more types you have (as opposed to more "else if"s with the
> > instanceof approach).
> >
> > A visitor itself can also do all sorts of things other than just
> > identify the type.
> >
> > That said, it's really a cosmetic difference either way and barely
> > worth the discussion -- your time is certainly better spent elsewhere!
> >
> > -Adam
> >
> >
> > On Feb 13, 2008 11:58 AM, 이희승 (Trustin Lee) <[EMAIL PROTECTED]> wrote:
> >> I am not sure if it's a more flexible solution considering we are going
> >> to have more transports. For example, we have serial port communication
> >> transport, and we will have to add a visit method per each transport.
> >>
> >> Trustin
> >>
> >> 2008-02-13 (수), 09:58 -0500, Adam Fisk 쓰시길:
> >>
> >>> This would be a nice place for the good old visitor pattern, so
> >>> something like, in SocketSession,
> >>>
> >>> SocketSession implements VisitableSession
> >>>
> >>> ...
> >>> public void accept(final SessionVisitor visitor)
> >>> {
> >>> visitor.visitSocketSession(this);
> >>> }
> >>>
> >>> Then you have a lot of flexibility with the visitor itself to handle
> >>> types nicely. The SessionVisitor would be an interface like:
> >>>
> >>> public interface SessionVisitor
> >>> {
> >>> void visitSocketSocket(final SocketSession session);
> >>> void visitDatagramSession(final DatagramSession session);
> >>> }
> >>>
> >>> I'd be happy to make a patch along those lines if people were
> >>> interested. It would use generics for return types rather than the
> >>> above for slightly more flexibility.
> >>>
> >>> -Adam
> >>>
> >>>
> >>> On Feb 13, 2008 12:06 AM, 이희승 (Trustin Lee) <[EMAIL PROTECTED]> wrote:
> >>>> 2008-01-28 (월), 10:47 -0400, Brenno Hayden 쓰시길:
> >>>>> Hello ,
> >>>>> i have same doubt..
> >>>>> - How can I tell if the connection is udp or tcp?
> >>>> In 1.x, you can use IoSession.getTransportType(). In 2.x, you can
> >>>> simply use 'instanceof SocketSession' or 'instanceof DatagramSession'.
> >>>>
> >>>> --
> >>>> what we call human nature is actually human habit
> >>>> --
> >>>> http://gleamynode.net/
> >>>>
> >>>
> >>>
> >> --
> >> what we call human nature is actually human habit
> >> --
> >> http://gleamynode.net/
> >>
> >
> >
> >
>
>
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