[openbeos] Re: state-keeping app
- From: "Ingo Weinhold" <bonefish@xxxxxxxxxxxxxxx>
- To: openbeos@xxxxxxxxxxxxx
- Date: Thu, 01 Aug 2002 23:49:56 CEST (+0200)
> En réponse à Jonas Sundstrom <kirilla@xxxxxxxxx>:
>
> > I'd do it something like this:
> >
> > - a new resource flag: "Remember state"
> > (something like that)
> >
> > - a B_LOAD_STATE app launch message
> >
> > - a B_SAVE_STATE shutdown message
> > (probably a B_QUIT_REQUESTED with a "save_state" field)
Actually I would provide the application programmer with a little bit
more comfortable interface. E.g. two new BApplication hook methods
status_t StoreState(BDataIO *state);
status_t RestoreState(BDataIO *state);
A BDataIO should be better than a BMessage, as applications with a
greater amount of data to be saved/loaded certainly don't want to put
it into a BMessage first, whereas the others are free to internally use
a BMessage and just Flatten() it to/Unflatten() it from the BDataIO.
> Yeah, I'm pretty sure the shutdown command just sends
> B_QUIT_REQUESTED with
> a special flag on the BMessage, can't remember where I read that
> though.
Actually the registrar is the one responsible for system shutdown and
it the flag you mean is the boolean field "_shutdown_".
> > The resource flag would keep non-state-aware apps
> > out of the loop
> >
> Or just those that ignore the flag on QUIT_REQUESTED ?
>
> > The load/save messages would put the actual
> > state-management in the hands of the application.
> > (different apps - different ways of saving state)
> >
> > All backwards-compatible with Be's R5.
So are hook methods. The BApplication implementation would just return
B_UNSUPPORTED or another meaningful error.
CU, Ingo
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