Paul Davis <[EMAIL PROTECTED]> writes:
> you're not the only ones; i've discussed this issue several times on
> this list in the past.
o Thanks for your analyses (below). As I said originally, I've
searched the archives for this, but never found the right
keywords. Could you provide some "Subject:" lines? Searching for
your name doesn't help -- you post too much to the lists. (This is
a compliment, not a complaint.)
> however, if you're really doing
> Model-View-Controller style programming, which is highly desirable and
> it sounds as if you are, then Havoc's suggestion of:
>
> handle_widget_state_change () {
> if (widget->representation_of_object_state() != object->state())
> widget->set_state (object->state());
> }
>
> is the *only* correct route to take here.
o I (possibly mis-) read Havoc's:
> if (current_state == gtk_toggle_button_get_active (toggle))
> return;
a little differently. If his "current_state" is your
"object->state()" (which makes more sense than my interpretation of
"widget->previous_state()"), and if "handle_widget_state_change()"
is a GTK signal-handler/callback, I would think it should be:
handle_widget_state_change () {
if (widget->representation_of_object_state() != object->state())
object->set_state (widget->state());
}
in order to break the feedback loop that causes me problems:
1) object ("Model") state changes
2) object changes widget X ("View") state
3) widget X is also a "Controller", thus emits a signal which is
caught by a signal handler which changes object's state
4) loop back to 1)
> in my C++ code, i tend to use a void * (aka gpointer) as an extra arg
> to all functions that change the state of my objects ("models"), an
> arg i call "src". when the objects emit signals as a result of the
> change, they include the "src" argument. as a result, widgets ("views"
> and/or "controllers") can do things like:
>
> handle_widget_state_change (void *src) {
> if (src == this) {
> /* ignore */
> return;
> }
> ....
> }
>
> this lets a widget set the state of its underlying object (when acting
> as a controller), supplying "itself" as the src pointer, and thus
> ignore any notifications from the object when they are sent following
> the object's state change.
o Is the "this" in the above code fragment the object (Model) or the
widget (View/Controller)? If object/Model, I don't understand
because mine don't emit signals (widgets/Controllers emit signals;
objects/Models do things like gtk_toggle_button_set_active()). If
"this" is the widget/Controller, when "src==this" is exactly when
the action should take place.
--
MARK
[EMAIL PROTECTED]
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