calendar: Define EventSourceBase and extend EventSource's

Objects implementing EventSource should have some mandatory methods and
properties, we can ensure this by defining an EventSourceBase abstract
class.

So inherit EmptyEventSource and DBusEventSource from it making sure that
they implement all the needed methods, using native properties and
replacing the 'notify::*' fake signal emissions with proper object
notifications.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/563

js/ui/calendar.js

@@ -1,8 +1,7 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
-/* exported Calendar, CalendarMessageList */
+/* exported Calendar, CalendarMessageList, DBusEventSource */
 
 const { Clutter, Gio, GLib, GObject, Shell, St } = imports.gi;
-const Signals = imports.signals;
 
 const Main = imports.ui.main;
 const MessageList = imports.ui.messageList;
@@ -99,17 +98,54 @@ var CalendarEvent = class CalendarEvent {
 // Interface for appointments/events - e.g. the contents of a calendar
 //
 
-// First, an implementation with no events
-var EmptyEventSource = class EmptyEventSource {
-    constructor() {
-        this.isLoading = false;
-        this.isDummy = true;
-        this.hasCalendars = false;
+var EventSourceBase = GObject.registerClass({
+    GTypeFlags: GObject.TypeFlags.ABSTRACT,
+    Properties: {
+        'has-calendars': GObject.ParamSpec.boolean(
+            'has-calendars', 'has-calendars', 'has-calendars',
+            GObject.ParamFlags.READABLE,
+            false),
+        'is-loading': GObject.ParamSpec.boolean(
+            'is-loading', 'is-loading', 'is-loading',
+            GObject.ParamFlags.READABLE,
+            false),
+    },
+    Signals: { 'changed': {} }
+}, class EventSourceBase extends GObject.Object {
+    get isLoading() {
+        throw new GObject.NotImplementedError(`isLoading in ${this.constructor.name}`);
+    }
+
+    get hasCalendars() {
+        throw new GObject.NotImplementedError(`hasCalendars in ${this.constructor.name}`);
     }
 
     destroy() {
     }
 
+    requestRange(_begin, _end) {
+        throw new GObject.NotImplementedError(`requestRange in ${this.constructor.name}`);
+    }
+
+    getEvents(_begin, _end) {
+        throw new GObject.NotImplementedError(`getEvents in ${this.constructor.name}`);
+    }
+
+    hasEvents(_day) {
+        throw new GObject.NotImplementedError(`hasEvents in ${this.constructor.name}`);
+    }
+});
+
+var EmptyEventSource = GObject.registerClass(
+class EmptyEventSource extends EventSourceBase {
+    get isLoading() {
+        return false;
+    }
+
+    get hasCalendars() {
+        return false;
+    }
+
     requestRange(_begin, _end) {
     }
 
@@ -121,8 +157,7 @@ var EmptyEventSource = class EmptyEventSource {
     hasEvents(_day) {
         return false;
     }
-};
-Signals.addSignalMethods(EmptyEventSource.prototype);
+});
 
 const CalendarServerIface = loadInterfaceXML('org.gnome.Shell.CalendarServer');
 
@@ -154,11 +189,12 @@ function _dateIntervalsOverlap(a0, a1, b0, b1) {
 }
 
 // an implementation that reads data from a session bus service
-var DBusEventSource = class DBusEventSource {
-    constructor() {
+var DBusEventSource = GObject.registerClass(
+class DBusEventSource extends EventSourceBase {
+    _init() {
+        super._init();
         this._resetCache();
-        this.isLoading = false;
-        this.isDummy = false;
+        this._isLoading = false;
 
         this._initialized = false;
         this._dbusProxy = new CalendarServer();
@@ -193,12 +229,12 @@ var DBusEventSource = class DBusEventSource {
             });
 
             this._dbusProxy.connect('g-properties-changed', () => {
-                this.emit('notify::has-calendars');
+                this.notify('has-calendars');
             });
 
             this._initialized = loaded;
             if (loaded) {
-                this.emit('notify::has-calendars');
+                this.notify('has-calendars');
                 this._onNameAppeared();
             }
         });
@@ -215,6 +251,10 @@ var DBusEventSource = class DBusEventSource {
             return false;
     }
 
+    get isLoading() {
+        return this._isLoading;
+    }
+
     _resetCache() {
         this._events = [];
         this._lastRequestBegin = null;
@@ -252,7 +292,7 @@ var DBusEventSource = class DBusEventSource {
         newEvents.sort((ev1, ev2) => ev1.date.getTime() - ev2.date.getTime());
 
         this._events = newEvents;
-        this.isLoading = false;
+        this._isLoading = false;
         this.emit('changed');
     }
 
@@ -272,7 +312,7 @@ var DBusEventSource = class DBusEventSource {
 
     requestRange(begin, end) {
         if (!(_datesEqual(begin, this._lastRequestBegin) && _datesEqual(end, this._lastRequestEnd))) {
-            this.isLoading = true;
+            this._isLoading = true;
             this._lastRequestBegin = begin;
             this._lastRequestEnd = end;
             this._curRequestBegin = begin;
@@ -310,8 +350,7 @@ var DBusEventSource = class DBusEventSource {
 
         return true;
     }
-};
-Signals.addSignalMethods(DBusEventSource.prototype);
+});
 
 var Calendar = GObject.registerClass({
     Signals: { 'selected-date-changed': { param_types: [GLib.DateTime.$gtype] } }
@@ -355,9 +394,10 @@ var Calendar = GObject.registerClass({
         this._buildHeader ();
     }
 
-    // @eventSource: is an object implementing the EventSource API, e.g. the
-    // requestRange(), getEvents(), hasEvents() methods and the ::changed signal.
     setEventSource(eventSource) {
+        if (!(eventSource instanceof EventSourceBase))
+            throw new Error('Event source is not valid type');
+
         this._eventSource = eventSource;
         this._eventSource.connect('changed', () => {
             this._rebuildCalendar();
@@ -566,7 +606,7 @@ var Calendar = GObject.registerClass({
                                          can_focus: true });
             let rtl = button.get_text_direction() == Clutter.TextDirection.RTL;
 
-            if (this._eventSource.isDummy)
+            if (this._eventSource instanceof EmptyEventSource)
                 button.reactive = false;
 
             button._date = new Date(iter);
@@ -802,6 +842,9 @@ class EventsSection extends MessageList.MessageListSection {
     }
 
     setEventSource(eventSource) {
+        if (!(eventSource instanceof EventSourceBase))
+            throw new Error('Event source is not valid type');
+
         this._eventSource = eventSource;
         this._eventSource.connect('changed', this._reloadEvents.bind(this));
     }