[gnome-shell] calendar: Define EventSourceBase and extend EventSource's

[Florian Müllner <fmuellner src gnome org>]

commit 5e43f282a1ebb55cf051fe01052f5d64def3d72c
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed May 29 07:52:17 2019 +0200

    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 | 89 +++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 66 insertions(+), 23 deletions(-)
---
diff --git a/js/ui/calendar.js b/js/ui/calendar.js
index 7d6c931554..e4d8be922b 100644
--- a/js/ui/calendar.js
+++ b/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));
     }