Re: [Vala] Proposal for asynchronous DBus calls.

["Christian Hergert" <christian hergert gmail com>]

Totally.  Like I said, not really applicable, but figured I'd mention it.

With closures, the framework will stay the same, you just get access
to more locals as your user_data wont get hi-jacked by the instance,
but the closure data.

-- Christian

On Fri, Oct 17, 2008 at 2:25 AM, Sam Liddicott <sam liddicott com> wrote:
> * Christian Hergert wrote, On 17/10/08 09:24:
> > For tasks, you have two options.
> >
> > 1) Create a GTask with a callback and user_data.
> > 2) Inherit from GTask and implement the execute (and optionally,
> > cancel) methods.
> >
> > Keen observers will notice my challenge right away. Yes, I inherit
> > from GObject for reference counting and general ease of use.  It was a
> > tough choice.  That may make scalability an interesting feat without
> > reusing tasks with a sort of free-list (a la threading building
> > blocks).
> >
> > Point being, your shared variables will live in the "target" of your GTaskFunc.
> >
> > And the prototype for sake of link jumping.
> >
> > typedef GTask* (*GTaskFunc) (GTask *task, GError **error, gpointer user_data);
> >
> > Notice how a task/callback/errback can pause further execution of the
> > state machine by returning another task immediately.  Errback's will
> > have the option to free and unset error to allow for further
> > processing of the callback chain.  Not quite sure how to handle this
> > in vala bindings yet. I'm considering dropping error from the
> > prototype and adding it as tasks methods (task.{get/set}_error).
> heh.
>
> I want to do async handlers in order to avoid writing the state machine,
> and to avoid having to declare a class with all my shared variables.
>
> I want to write a linear function and "not mind" if it gets broken up.
>
> I suspect this is because I am user of someone elses async framework,
> you are trying to devise an async framework.
>
> Sam
> > -- Christian
> >
> > On Fri, Oct 17, 2008 at 1:05 AM, Sam Liddicott <sam liddicott com> wrote:
> >
> > > * Christian Hergert wrote, On 17/10/08 08:06:
> > >
> > > > This isn't totally applicable, but I thought I'd mention it before too
> > > > much more async voodo.
> > > >
> > > > I've been working on an asynchronous toolkit library for GObject so
> > > > that once we get "yield return/yield break" support I can implement my
> > > > ideas I posted earlier.
> > > >
> > > > The library is called GTask and can be found on github[1].  For a
> > > > quick, totally out of context example:
> > > >
> > > > var task = new Task (_ => {
> > > >     debug ("im in worker thread");
> > > > });
> > > >
> > > > task.add_callback (_ => {
> > > >     debug ("im in main thread, by default");
> > > > });
> > > >
> > > > task.add_errback (_ => {
> > > >     debug ("i can resolve an asynchronous error");
> > > > });
> > > >
> > > > You can build complex callback/errback chains just like in Python
> > > > Twisted.  By default, the task scheduler will dispatch callbacks and
> > > > errbacks from the main thread to ease locking hell for GUI
> > > This looks a similar pattern to that used in samba's composite connect;
> > > I think it is useful.
> > >
> > > How will shared variables be expressed?
> > >
> > > Sam