QtNetwork (examples) - update multicastsender

Similar to broadcast sender:

- where possible use local variables instead of data-members
- where possible avoid heap-allocated objects, use sub-objects instead
- change signal-slot connection syntax (and as a "bonus" - show our QOverload)

Task-number: QTBUG-60628
Change-Id: I8cd4f888c1d0653bdc8591800e713bbd347ad2fb
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

examples/network/multicastsender/sender.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the examples of the Qt Toolkit.
@@ -48,43 +48,35 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
-#include <QtNetwork>
-
 #include "sender.h"
 
 Sender::Sender(QWidget *parent)
-    : QDialog(parent)
+    : QDialog(parent),
+      groupAddress(QStringLiteral("239.255.43.21"))
 {
-    groupAddress = QHostAddress("239.255.43.21");
-
     statusLabel = new QLabel(tr("Ready to multicast datagrams to group %1 on port 45454").arg(groupAddress.toString()));
 
-    ttlLabel = new QLabel(tr("TTL for multicast datagrams:"));
-    ttlSpinBox = new QSpinBox;
+    auto ttlLabel = new QLabel(tr("TTL for multicast datagrams:"));
+    auto ttlSpinBox = new QSpinBox;
     ttlSpinBox->setRange(0, 255);
 
-    QHBoxLayout *ttlLayout = new QHBoxLayout;
+    auto ttlLayout = new QHBoxLayout;
     ttlLayout->addWidget(ttlLabel);
     ttlLayout->addWidget(ttlSpinBox);
 
     startButton = new QPushButton(tr("&Start"));
-    quitButton = new QPushButton(tr("&Quit"));
+    auto quitButton = new QPushButton(tr("&Quit"));
 
-    buttonBox = new QDialogButtonBox;
+    auto buttonBox = new QDialogButtonBox;
     buttonBox->addButton(startButton, QDialogButtonBox::ActionRole);
     buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);
 
-    timer = new QTimer(this);
-    udpSocket = new QUdpSocket(this);
-    messageNo = 1;
+    connect(ttlSpinBox, QOverload<int>::of(&QSpinBox::valueChanged), this, &Sender::ttlChanged);
+    connect(startButton, &QPushButton::clicked, this, &Sender::startSending);
+    connect(quitButton, &QPushButton::clicked, this, &Sender::close);
+    connect(&timer, &QTimer::timeout, this, &Sender::sendDatagram);
 
-    connect(ttlSpinBox, SIGNAL(valueChanged(int)), this, SLOT(ttlChanged(int)));
-    connect(startButton, SIGNAL(clicked()), this, SLOT(startSending()));
-    connect(quitButton, SIGNAL(clicked()), this, SLOT(close()));
-    connect(timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));
-
-    QVBoxLayout *mainLayout = new QVBoxLayout;
+    auto mainLayout = new QVBoxLayout;
     mainLayout->addWidget(statusLabel);
     mainLayout->addLayout(ttlLayout);
     mainLayout->addWidget(buttonBox);
@@ -96,20 +88,19 @@ Sender::Sender(QWidget *parent)
 
 void Sender::ttlChanged(int newTtl)
 {
-    udpSocket->setSocketOption(QAbstractSocket::MulticastTtlOption, newTtl);
+    udpSocket.setSocketOption(QAbstractSocket::MulticastTtlOption, newTtl);
 }
 
 void Sender::startSending()
 {
     startButton->setEnabled(false);
-    timer->start(1000);
+    timer.start(1000);
 }
 
 void Sender::sendDatagram()
 {
     statusLabel->setText(tr("Now sending datagram %1").arg(messageNo));
     QByteArray datagram = "Multicast message " + QByteArray::number(messageNo);
-    udpSocket->writeDatagram(datagram.data(), datagram.size(),
-                             groupAddress, 45454);
+    udpSocket.writeDatagram(datagram, groupAddress, 45454);
     ++messageNo;
 }

examples/network/multicastsender/sender.h

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the examples of the Qt Toolkit.
@@ -51,24 +51,16 @@
 #ifndef SENDER_H
 #define SENDER_H
 
-#include <QDialog>
-#include <QHostAddress>
-
-QT_BEGIN_NAMESPACE
-class QDialogButtonBox;
-class QLabel;
-class QPushButton;
-class QTimer;
-class QUdpSocket;
-class QSpinBox;
-QT_END_NAMESPACE
+#include <QtWidgets>
+#include <QtNetwork>
+#include <QtCore>
 
 class Sender : public QDialog
 {
     Q_OBJECT
 
 public:
-    Sender(QWidget *parent = 0);
+    explicit Sender(QWidget *parent = nullptr);
 
 private slots:
     void ttlChanged(int newTtl);
@@ -76,16 +68,12 @@ private slots:
     void sendDatagram();
 
 private:
-    QLabel *statusLabel;
-    QLabel *ttlLabel;
-    QSpinBox *ttlSpinBox;
-    QPushButton *startButton;
-    QPushButton *quitButton;
-    QDialogButtonBox *buttonBox;
-    QUdpSocket *udpSocket;
-    QTimer *timer;
+    QLabel *statusLabel = nullptr;
+    QPushButton *startButton = nullptr;
+    QUdpSocket udpSocket;
+    QTimer timer;
     QHostAddress groupAddress;
-    int messageNo;
+    int messageNo = 1;
 };
 
 #endif