Bind to multiple properties simultaneously

[popov895 (Eugene Popov)]

Is there any way in GJS to bind a property to multiple properties simultaneously? For example, I have three buttons and the third button should only be enabled only if the other two buttons are checked? Something like property binding in QML.

[ebassi (Emmanuele Bassi)]

There is no direct way to make a property binding conditional on multiple properties, but you can the underlying property notification mechanism to write your own property binding:

this._button1.connect("notify::active", () => {
    if (this._button1.get_active() && this._button2.get_active()) {
        this._button3.set_sensitive(true);
    } else {
        this._button3.set_sensitive(false);
    }
});
this._button2.connect("notify::active", () => {
    if (this._button1.get_active() && this._button2.get_active()) {
        this._button3.set_sensitive(true);
    } else {
        this._button3.set_sensitive(false);
    }
});

You can, of course, abstract the signal handler into its own function:

_enableThirdButton() {
    this._button3.set_sensitive(this._button1.get_active() && this._button2.get_active());
}

// ...

this._button1.connect("notify::active", this._enableThirdButton.bind(this));
this._button2.connect("notify::active", this._enableThirdButton.bind(this));