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/ui/status/keyboard.js

@@ -3,7 +3,7 @@
 
 const { Clutter, Gio, GLib, GObject, IBus, Meta, Shell, St } = imports.gi;
 const Gettext = imports.gettext;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const IBusManager = imports.misc.ibusManager;
 const KeyboardManager = imports.misc.keyboardManager;
@@ -32,8 +32,10 @@ class LayoutMenuItem extends PopupMenu.PopupBaseMenuItem {
     }
 });
 
-var InputSource = class {
+var InputSource = class extends Signals.EventEmitter {
     constructor(type, id, displayName, shortName, index) {
+        super();
+
         this.type = type;
         this.id = id;
         this.displayName = displayName;
@@ -69,7 +71,6 @@ var InputSource = class {
             return engineDesc.layout;
     }
 };
-Signals.addSignalMethods(InputSource.prototype);
 
 var InputSourcePopup = GObject.registerClass(
 class InputSourcePopup extends SwitcherPopup.SwitcherPopup {
@@ -135,8 +136,10 @@ class InputSourceSwitcher extends SwitcherPopup.SwitcherList {
     }
 });
 
-var InputSourceSettings = class {
+var InputSourceSettings = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         if (this.constructor === InputSourceSettings)
             throw new TypeError(`Cannot instantiate abstract class ${this.constructor.name}`);
     }
@@ -173,7 +176,6 @@ var InputSourceSettings = class {
         return false;
     }
 };
-Signals.addSignalMethods(InputSourceSettings.prototype);
 
 var InputSourceSystemSettings = class extends InputSourceSettings {
     constructor() {
@@ -300,8 +302,10 @@ var InputSourceSessionSettings = class extends InputSourceSettings {
     }
 };
 
-var InputSourceManager = class {
+var InputSourceManager = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         // All valid input sources currently in the gsettings
         // KEY_INPUT_SOURCES list indexed by their index there
         this._inputSources = {};
@@ -771,7 +775,6 @@ var InputSourceManager = class {
         return this._keyboardManager;
     }
 };
-Signals.addSignalMethods(InputSourceManager.prototype);
 
 let _inputSourceManager = null;
 

js/ui/status/network.js

@@ -1,7 +1,7 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 /* exported NMApplet */
 const { Clutter, Gio, GLib, GObject, Meta, NM, Polkit, St } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const Animation = imports.ui.animation;
 const Main = imports.ui.main;
@@ -107,8 +107,10 @@ function launchSettingsPanel(panel, ...args) {
     }
 }
 
-var NMConnectionItem = class {
+var NMConnectionItem = class extends Signals.EventEmitter {
     constructor(section, connection) {
+        super();
+
         this._section = section;
         this._connection = connection;
         this._activeConnection = null;
@@ -193,10 +195,11 @@ var NMConnectionItem = class {
         this._sync();
     }
 };
-Signals.addSignalMethods(NMConnectionItem.prototype);
 
-var NMConnectionSection = class NMConnectionSection {
+var NMConnectionSection = class NMConnectionSection extends Signals.EventEmitter {
     constructor(client) {
+        super();
+
         if (this.constructor === NMConnectionSection)
             throw new TypeError(`Cannot instantiate abstract type ${this.constructor.name}`);
 
@@ -320,7 +323,6 @@ var NMConnectionSection = class NMConnectionSection {
         this._sync();
     }
 };
-Signals.addSignalMethods(NMConnectionSection.prototype);
 
 var NMConnectionDevice = class NMConnectionDevice extends NMConnectionSection {
     constructor(client, device) {
@@ -1242,8 +1244,10 @@ class NMWirelessDialog extends ModalDialog.ModalDialog {
     }
 });
 
-var NMDeviceWireless = class {
+var NMDeviceWireless = class extends Signals.EventEmitter {
     constructor(client, device) {
+        super();
+
         this._client = client;
         this._device = device;
 
@@ -1433,7 +1437,6 @@ var NMDeviceWireless = class {
             return 'network-wireless-no-route-symbolic';
     }
 };
-Signals.addSignalMethods(NMDeviceWireless.prototype);
 
 var NMWireguardItem = class extends NMConnectionItem {
     _buildUI() {
@@ -1657,7 +1660,6 @@ var NMVpnSection = class extends NMConnectionSection {
         return '';
     }
 };
-Signals.addSignalMethods(NMVpnSection.prototype);
 
 var DeviceCategory = class extends PopupMenu.PopupMenuSection {
     constructor(category) {

js/ui/status/rfkill.js

@@ -2,7 +2,7 @@
 /* exported Indicator */
 
 const { Gio, GObject } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const Main = imports.ui.main;
 const PanelMenu = imports.ui.panelMenu;
@@ -16,18 +16,20 @@ const OBJECT_PATH = '/org/gnome/SettingsDaemon/Rfkill';
 const RfkillManagerInterface = loadInterfaceXML('org.gnome.SettingsDaemon.Rfkill');
 const RfkillManagerProxy = Gio.DBusProxy.makeProxyWrapper(RfkillManagerInterface);
 
-var RfkillManager = class {
+var RfkillManager = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         this._proxy = new RfkillManagerProxy(Gio.DBus.session, BUS_NAME, OBJECT_PATH,
-                                             (proxy, error) => {
-                                                 if (error) {
-                                                     log(error.message);
-                                                     return;
-                                                 }
-                                                 this._proxy.connect('g-properties-changed',
-                                                                     this._changed.bind(this));
-                                                 this._changed();
-                                             });
+            (proxy, error) => {
+                if (error) {
+                    log(error.message);
+                    return;
+                }
+                this._proxy.connect('g-properties-changed',
+                    this._changed.bind(this));
+                this._changed();
+            });
     }
 
     get airplaneMode() {
@@ -50,7 +52,6 @@ var RfkillManager = class {
         this.emit('airplane-mode-changed');
     }
 };
-Signals.addSignalMethods(RfkillManager.prototype);
 
 var _manager;
 function getRfkillManager() {

js/ui/status/thunderbolt.js

@@ -4,7 +4,7 @@
 // the following is a modified version of bolt/contrib/js/client.js
 
 const { Gio, GLib, GObject, Polkit, Shell } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const Main = imports.ui.main;
 const MessageTray = imports.ui.messageTray;
@@ -49,8 +49,10 @@ const BOLT_DBUS_CLIENT_IFACE = 'org.freedesktop.bolt1.Manager';
 const BOLT_DBUS_NAME = 'org.freedesktop.bolt';
 const BOLT_DBUS_PATH = '/org/freedesktop/bolt';
 
-var Client = class {
+var Client = class extends Signals.EventEmitter {
     constructor() {
+        super();
+
         this._proxy = null;
         this.probing = false;
         this._getProxy();
@@ -127,11 +129,12 @@ var Client = class {
         return this._proxy.AuthMode;
     }
 };
-Signals.addSignalMethods(Client.prototype);
 
 /* helper class to automatically authorize new devices */
-var AuthRobot = class {
+var AuthRobot = class extends Signals.EventEmitter {
     constructor(client) {
+        super();
+
         this._client = client;
 
         this._devicesToEnroll = [];
@@ -217,7 +220,6 @@ var AuthRobot = class {
         return GLib.SOURCE_REMOVE;
     }
 };
-Signals.addSignalMethods(AuthRobot.prototype);
 
 /* eof client.js  */
 

js/ui/status/volume.js

@@ -2,7 +2,7 @@
 /* exported Indicator */
 
 const { Clutter, Gio, GLib, GObject, Gvc, St } = imports.gi;
-const Signals = imports.signals;
+const Signals = imports.misc.signals;
 
 const Main = imports.ui.main;
 const PanelMenu = imports.ui.panelMenu;
@@ -29,8 +29,10 @@ function getMixerControl() {
     return _mixerControl;
 }
 
-var StreamSlider = class {
+var StreamSlider = class extends Signals.EventEmitter {
     constructor(control) {
+        super();
+
         this._control = control;
 
         this.item = new PopupMenu.PopupBaseMenuItem({ activate: false });
@@ -213,7 +215,6 @@ var StreamSlider = class {
         return maxVolume / this._control.get_vol_max_norm();
     }
 };
-Signals.addSignalMethods(StreamSlider.prototype);
 
 var OutputStreamSlider = class extends StreamSlider {
     constructor(control) {