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
defadd_radio(model:Gio.SimpleAction,id:str,label:str):button=Gtk.CheckButton(label=label)# Tell this button to activate when the model has the given valuebutton.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 statedetailed_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 selectedifnotmodel.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))