[Glade-devel] Property Binding: Fixing the big blocker
Denis Washington
denisw at online.de
Fri Nov 18 02:24:27 EST 2011
Am 15.11.2011 22:44, schrieb Tristan Van Berkom:
> I think that it's obvious the mechanism is needed, but I dont think that we
> should clear bindings based on sensitivity state, in other words I would much
> rather that sensitivity always be the last thing which is evaluated based
> on other real states (it doesnt seem to make sense that we drive a 'real'
> project state based on the 'virtual' sensitivity state, and I fear with the
> complexity of Glade that that will bite us later on).
>
> So, for the scenario you described above, functionally speaking I
> think this needs
> to happen:
>
> o Button editor sets the edit mode and does glade_command_push_group()
> o Button editor does it's normal command group routines
> o Button editor invalidates the "label" property (note: this
> invalidation does not exist)
> o Invalidating the "label" property causes bindings to that label to
> become invalid, in
> fact anything which "refers to that property" is invalid, today
> this can only be a binding
> of another property.
> o A widget has a property which was bound to the "label"
> property which was invalidated,
> as a consequence of that action, it's binding to the said
> label is undoably cleared
> o GladeWidgetAdaptor->evaluate_sensitivity ( use_command = TRUE
> ) is called on
> that target property's widget to re-evaluate sensitivity
> states after having changed
> the binding state
> o All widgets with any binding to the invalidated label finish
> adjusting themselves to the
> invalidation
> o Button editor calls GladeWidgetAdaptor->evaluate_sensitivity (
> use_command = TRUE )
> on itself to evaluate the sensitivity after having changed it's
> own "edit mode"
> o Finally glade_command_pop_group() is hit
>
> The "invalidation" above might be a signal from the source
> GladeProperty which has
> a strict meaning, or possibly just a function
> glade_command_property_invalidate()
> which loops over all the targets, unsets them and resolves the
> sensitivity of the
> target widget.
I am not sure how the additional "invalidation" command you envision
would conceptually differ from glade_command_set_sensitive (sensitive =
FALSE). While I understand your intention, the fact that the property
sensitivity *does* affect the binding state still remains in your
proposed design; it is just indirected by the "invalidate" command.
Also, the "invalidation" logic in the Editor would inevitably duplicate
the logic in GladeWidgetAdaptor->evaluate_property_flags() (or
->evaluate_sensitivity(), we we're going to call it), meaning that
changes to that logic alway requires modifications to two places
(error-prone). In short, I think this needlessly complicates things
without benefit.
For reference, this is how the process works currently in the
"command-set-sensitive" branch:
1. The Editor does glade_command_group_push() and does what it has
always done.
2. Editor calls "GladeWidgetAdaptor->adjust_property_flags (use_command
= TRUE)". That function's implementation uses
glade_command_set_property_sensitive(), which checks whether any
bindings become invalidated by the sensitivity change and, in turn,
calls "glade_command_bind_property (binding_target, NULL)" as needed
(grouped with the original sensitivity-setting command).
3. Editor calls glade_command_pop_group().
On loading a widget, ->adjust_property_flags() with use_command=FALSE is
called.
Regards,
Denis
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