Gtk4 has interesting ways of splitting models and views. One that I didn't find very well documented, especially for Python bindings, is a set of radio buttons backed by a common model.
The idea is to define an action that takes a string as a state. Each radio button is assigned a string matching one of the possible states, and when the state of the backend action is changed, the radio buttons are automatically updated.
All the examples below use a string for a value type, but anything can be used
that fits into a GLib.Variant.
The model
This defines the action. Note that enables all the usual declarative ways of a status change:
mode = Gio.SimpleAction.new_stateful(
name="mode-selection",
parameter_type=GLib.VariantType("s"),
state=GLib.Variant.new_string(""))
gtk_app.add_action(self.mode)
The view
def add_radio(model: Gio.SimpleAction, id: str, label: str):
button = Gtk.CheckButton(label=label)
# Tell this button to activate when the model has the given value
button.set_action_target_value(GLib.Variant.new_string(id))
# Build the name under which the action is registesred, plus the state
# value controlled by this button: clicking the button will set this state
detailed_name = Gio.Action.print_detailed_name(
"app." + model.get_name(),
GLib.Variant.new_string(id))
button.set_detailed_action_name(detailed_name)
# If the model has no current value set, this sets the first radio button
# as selected
if not model.get_state().get_string():
model.set_state(GLib.Variant.new_string(id))
Accessing the model
To read the currently selected value:
current = model.get_state().get_string()
To set the currently selected value:
model.set_state(GLib.Variant.new_string(id))