On Fri, 2006-07-07 at 22:42 +0300, Paul Pogonyshev wrote:
> Currently, you have to 1) set sensitivity (some state) to a computed value;
> 2) track when that computed value changes its state, by connecting to the
> appropriate callbacks; if the rules change, you have to not forget to keep
> the computation and state tracking in sync; and 3) set the initial state
> (sometimes). Note that the initial state should also be in sync with
> points 1) and 2).
>
> I propose to do all the steps at once, using `condition's. This roughly
> corresponds to step 1), while all the rest is done automatically.
>
> Using conditions (doesn't work currently, of course; how it should look
> like):
>
> button->set_sensitive (entry->get_not_empty_condition () &
> check_button->get_active_condition ());
This is an interesting idea, but I have no idea how you might implement
it.
> Traditional method:
>
> entry->signal_changed ().connect (sigc::mem_fun (*this,
> &Windows::update_sensitivity));
> check_button->signal_toggled ().connect (sigc::mem_fun (*this,
> &Windows::update_sensitivity));
>
> // Set initial state.
> update_sensitivity ();
>
> ...
>
> void
> update_sensitivity ()
> {
> button->set_sensitive (entry->get_text_length () > 0 &&
> check_button->get_active ());
> }
Yes, I do this quite often.
> > Note also that you can already get notification of property changes from
> > gtkmm objects, like so:
> > widget.property_something().signal_changed().connect( ... )
>
> Yes. I propose to simplify it (writing less code) and make less error-
> prone (all is done only once and in one place.) This is at a small
> cost to efficiency, which is not important in GUI.
>
> Paul
--
Murray Cumming
[EMAIL PROTECTED]
www.murrayc.com
www.openismus.com
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