Adopt EventEmitter class instead of injecting Signal methods

Introduce a new class, EventEmitter, which implements signal
handling for pure JavaScript classes. EventEmitter still
utilizes GJS' addSignalMethods internally.

EventEmitter allows static typechecking to understand the
structure of event-emitting JS classes and makes creating
child classes simpler.

The name 'EventEmitter' mirrors a common name for this pattern
in Node and in JS libraries.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2043>

js/misc/history.js

@@ -1,13 +1,16 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+/* exported HistoryManager */
 
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 const Clutter = imports.gi.Clutter;
 const Params = imports.misc.params;
 
 var DEFAULT_LIMIT = 512;
 
-var HistoryManager = class {
+var HistoryManager = class extends Signals.EventEmitter {
     constructor(params) {
+        super();
+
         params = Params.parse(params, {
             gsettingsKey: null,
             limit: DEFAULT_LIMIT,
@@ -109,4 +112,3 @@ var HistoryManager = class {
             global.settings.set_strv(this._key, this._history);
     }
 };
-Signals.addSignalMethods(HistoryManager.prototype);

js/misc/ibusManager.js

@@ -2,7 +2,7 @@
 /* exported getIBusManager */
 
 const { Gio, GLib, IBus, Meta, Shell } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const IBusCandidatePopup = imports.ui.ibusCandidatePopup;
 
@@ -40,8 +40,10 @@ function getIBusManager() {
     return _ibusManager;
 }
 
-var IBusManager = class {
+var IBusManager = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         IBus.init();
 
         // This is the longest we'll keep the keyboard frozen until an input
@@ -325,4 +327,3 @@ var IBusManager = class {
                 });
     }
 };
-Signals.addSignalMethods(IBusManager.prototype);

js/misc/loginManager.js

@@ -2,7 +2,7 @@
 /* exported canLock, getLoginManager, registerSessionWithGDM */
 
 const { GLib, Gio } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const { loadInterfaceXML } = imports.misc.fileUtils;
 
@@ -87,8 +87,10 @@ function getLoginManager() {
     return _loginManager;
 }
 
-var LoginManagerSystemd = class {
+var LoginManagerSystemd = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         this._proxy = new SystemdLoginManager(Gio.DBus.system,
                                               'org.freedesktop.login1',
                                               '/org/freedesktop/login1');
@@ -202,9 +204,8 @@ var LoginManagerSystemd = class {
         this.emit('prepare-for-sleep', aboutToSuspend);
     }
 };
-Signals.addSignalMethods(LoginManagerSystemd.prototype);
 
-var LoginManagerDummy = class {
+var LoginManagerDummy = class extends Signals.EventEmitter  {
     getCurrentSessionProxy(_callback) {
         // we could return a DummySession object that fakes whatever callers
         // expect (at the time of writing: connect() and connectSignal()
@@ -236,4 +237,3 @@ var LoginManagerDummy = class {
         return null;
     }
 };
-Signals.addSignalMethods(LoginManagerDummy.prototype);

js/misc/objectManager.js

@@ -1,8 +1,9 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+/* exported ObjectManager */
 
 const { Gio, GLib } = imports.gi;
 const Params = imports.misc.params;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 // Specified in the D-Bus specification here:
 // http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-objectmanager
@@ -25,8 +26,10 @@ const ObjectManagerIface = `
 
 const ObjectManagerInfo = Gio.DBusInterfaceInfo.new_for_xml(ObjectManagerIface);
 
-var ObjectManager = class {
+var ObjectManager = class extends Signals.EventEmitter {
     constructor(params) {
+        super();
+
         params = Params.parse(params, {
             connection: null,
             name: null,
@@ -288,4 +291,3 @@ var ObjectManager = class {
         return proxies;
     }
 };
-Signals.addSignalMethods(ObjectManager.prototype);

js/misc/signalTracker.js

@@ -1,4 +1,4 @@
-/* exported TransientSignalHolder, addObjectSignalMethods */
+/* exported TransientSignalHolder, connectObject, disconnectObject */
 const { GObject } = imports.gi;
 
 const destroyableTypes = [];
@@ -214,25 +214,6 @@ function disconnectObject(thisObj, obj) {
     SignalManager.getDefault().getSignalTracker(thisObj).untrack(obj);
 }
 
-/**
- * Add connectObject()/disconnectObject() methods
- * to prototype. The prototype must have the connect()
- * and disconnect() signal methods.
- *
- * @param {prototype} proto - a prototype
- */
-function addObjectSignalMethods(proto) {
-    proto['connectObject'] = function (...args) {
-        connectObject(this, ...args);
-    };
-    proto['connect_object'] = proto['connectObject'];
-
-    proto['disconnectObject'] = function (obj) {
-        disconnectObject(this, obj);
-    };
-    proto['disconnect_object'] = proto['disconnectObject'];
-}
-
 /**
  * Register a GObject type as having a 'destroy' signal
  * that should disconnect all handlers

js/misc/signals.js

@@ -0,0 +1,22 @@
+const Signals = imports.signals;
+const SignalTracker = imports.misc.signalTracker;
+
+var EventEmitter = class EventEmitter {
+    connectObject(...args) {
+        return SignalTracker.connectObject(this, ...args);
+    }
+
+    disconnectObject(...args) {
+        return SignalTracker.disconnectObject(this, ...args);
+    }
+
+    connect_object(...args) {
+        return this.connectObject(...args);
+    }
+
+    disconnect_object(...args) {
+        return this.disconnectObject(...args);
+    }
+};
+
+Signals.addSignalMethods(EventEmitter.prototype);

js/misc/smartcardManager.js

@@ -2,7 +2,7 @@
 /* exported getSmartcardManager */
 
 const Gio = imports.gi.Gio;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const ObjectManager = imports.misc.objectManager;
 
@@ -25,8 +25,10 @@ function getSmartcardManager() {
     return _smartcardManager;
 }
 
-var SmartcardManager = class {
+var SmartcardManager = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         this._objectManager = new ObjectManager.ObjectManager({
             connection: Gio.DBus.session,
             name: 'org.gnome.SettingsDaemon.Smartcard',
@@ -114,4 +116,3 @@ var SmartcardManager = class {
         return true;
     }
 };
-Signals.addSignalMethods(SmartcardManager.prototype);

js/misc/weather.js

@@ -1,7 +1,8 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+/* exported WeatherClient */
 
 const { Geoclue, Gio, GLib, GWeather, Shell } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const PermissionStore = imports.misc.permissionStore;
 
@@ -20,8 +21,10 @@ const WEATHER_APP_ID = 'org.gnome.Weather.desktop';
 // Minimum time between updates to show loading indication
 var UPDATE_THRESHOLD = 10 * GLib.TIME_SPAN_MINUTE;
 
-var WeatherClient = class {
+var WeatherClient = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         this._loading = false;
         this._locationValid = false;
         this._lastUpdate = GLib.DateTime.new_from_unix_local(0);
@@ -319,4 +322,3 @@ var WeatherClient = class {
         this._updateAutoLocation();
     }
 };
-Signals.addSignalMethods(WeatherClient.prototype);