pingpong example: Modernize the code

Use qWarning()/std::cout instead of C IO functions.

Use default parameters for QDBusInterface's constructor.

Remove useless Q_SCRIPTABLE.

Use type-safe invokeMethod().

Extract a local variable for the used D-Bus connection.

Task-number: QTBUG-111366
Pick-to: 6.5
Change-Id: Idc38a7c1dd97d71308d9491193039744c759d6f2
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

3 files changed, 22 insertions, 24 deletions

diff --git a/examples/dbus/pingpong/ping.cpp b/examples/dbus/pingpong/ping.cpp
index 17f6b0e3cb..a217107835 100644
--- a/examples/dbus/pingpong/ping.cpp
+++ b/examples/dbus/pingpong/ping.cpp
@@ -8,32 +8,33 @@
 #include <QDBusInterface>
 #include <QDBusReply>
 
-#include <stdio.h>
+#include <iostream>
 
 int main(int argc, char **argv)
 {
     QCoreApplication app(argc, argv);
 
-    if (!QDBusConnection::sessionBus().isConnected()) {
-        fprintf(stderr, "Cannot connect to the D-Bus session bus.\n"
-                "To start it, run:\n"
-                "\teval `dbus-launch --auto-syntax`\n");
+    auto connection = QDBusConnection::sessionBus();
+
+    if (!connection.isConnected()) {
+        qWarning("Cannot connect to the D-Bus session bus.\n"
+                 "To start it, run:\n"
+                 "\teval `dbus-launch --auto-syntax`\n");
         return 1;
     }
 
-    QDBusInterface iface(SERVICE_NAME, "/", "", QDBusConnection::sessionBus());
+    QDBusInterface iface(SERVICE_NAME, "/");
     if (iface.isValid()) {
         QDBusReply<QString> reply = iface.call("ping", argc > 1 ? argv[1] : "");
         if (reply.isValid()) {
-            printf("Reply was: %s\n", qPrintable(reply.value()));
+            std::cout << "Reply was: " << qPrintable(reply.value()) << std::endl;
             return 0;
         }
 
-        fprintf(stderr, "Call failed: %s\n", qPrintable(reply.error().message()));
+        qWarning("Call failed: %s\n", qPrintable(reply.error().message()));
         return 1;
     }
 
-    fprintf(stderr, "%s\n",
-            qPrintable(QDBusConnection::sessionBus().lastError().message()));
+    qWarning("%s\n", qPrintable(connection.lastError().message()));
     return 1;
 }
diff --git a/examples/dbus/pingpong/pong.cpp b/examples/dbus/pingpong/pong.cpp
index 2aad1f10f7..6bcb9a6771 100644
--- a/examples/dbus/pingpong/pong.cpp
+++ b/examples/dbus/pingpong/pong.cpp
@@ -7,14 +7,10 @@
 #include <QCoreApplication>
 #include <QDBusConnection>
 #include <QDBusError>
-#include <QTimer>
-
-#include <stdio.h>
-#include <stdlib.h>
 
 QString Pong::ping(const QString &arg)
 {
-    QMetaObject::invokeMethod(QCoreApplication::instance(), "quit");
+    QMetaObject::invokeMethod(QCoreApplication::instance(), &QCoreApplication::quit);
     return QString("ping(\"%1\") got called").arg(arg);
 }
 
@@ -22,21 +18,22 @@ int main(int argc, char **argv)
 {
     QCoreApplication app(argc, argv);
 
-    if (!QDBusConnection::sessionBus().isConnected()) {
-        fprintf(stderr, "Cannot connect to the D-Bus session bus.\n"
-                "To start it, run:\n"
-                "\teval `dbus-launch --auto-syntax`\n");
+    auto connection = QDBusConnection::sessionBus();
+
+    if (!connection.isConnected()) {
+        qWarning("Cannot connect to the D-Bus session bus.\n"
+                 "To start it, run:\n"
+                 "\teval `dbus-launch --auto-syntax`\n");
         return 1;
     }
 
-    if (!QDBusConnection::sessionBus().registerService(SERVICE_NAME)) {
-        fprintf(stderr, "%s\n",
-                qPrintable(QDBusConnection::sessionBus().lastError().message()));
+    if (!connection.registerService(SERVICE_NAME)) {
+        qWarning("%s\n", qPrintable(connection.lastError().message()));
         exit(1);
     }
 
     Pong pong;
-    QDBusConnection::sessionBus().registerObject("/", &pong, QDBusConnection::ExportAllSlots);
+    connection.registerObject("/", &pong, QDBusConnection::ExportAllSlots);
 
     app.exec();
     return 0;
diff --git a/examples/dbus/pingpong/pong.h b/examples/dbus/pingpong/pong.h
index f683ec3dfb..2a99be9ca5 100644
--- a/examples/dbus/pingpong/pong.h
+++ b/examples/dbus/pingpong/pong.h
@@ -10,7 +10,7 @@ class Pong: public QObject
 {
     Q_OBJECT
 public slots:
-    Q_SCRIPTABLE QString ping(const QString &arg);
+    QString ping(const QString &arg);
 };
 
 #endif