Polish the modbus client example

- Use modern string literals
- Use QCommandLineParser to switch on verbose mode
- Fix translated texts with arguments
- Streamline some code
- Remove unused member variable
- Use QVariant casts

Change-Id: Ie3bdaa82856bfe8df020dc289de9177d098f02d3
Reviewed-by: Karsten Heimrich <karsten.heimrich@qt.io>
(cherry picked from commit 101295aef757747490fb5533710d9e10bf303d19)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 84 insertions, 59 deletions

diff --git a/examples/serialbus/modbus/client/main.cpp b/examples/serialbus/modbus/client/main.cpp
index 6e222ee..cbcf720 100644
--- a/examples/serialbus/modbus/client/main.cpp
+++ b/examples/serialbus/modbus/client/main.cpp
@@ -4,13 +4,27 @@
 #include "mainwindow.h"
 
 #include <QApplication>
+#include <QCommandLineParser>
+#include <QCommandLineOption>
 #include <QLoggingCategory>
 
+using namespace Qt::StringLiterals;
+
 int main(int argc, char *argv[])
 {
-    // Uncomment the following line to enable logging
-    // QLoggingCategory::setFilterRules(QStringLiteral("qt.modbus* = true"));
     QApplication a(argc, argv);
+
+    QCommandLineParser parser;
+    parser.setApplicationDescription(u"Modbus Client Example"_s);
+    parser.addHelpOption();
+    parser.addVersionOption();
+    QCommandLineOption verboseOption(u"verbose"_s, u"Verbose mode"_s);
+    parser.addOption(verboseOption);
+    parser.process(a);
+
+    if (parser.isSet(verboseOption))
+        QLoggingCategory::setFilterRules(u"qt.modbus* = true"_s);
+
     MainWindow w;
     w.show();
 
diff --git a/examples/serialbus/modbus/client/mainwindow.cpp b/examples/serialbus/modbus/client/mainwindow.cpp
index 7528f34..d505513 100644
--- a/examples/serialbus/modbus/client/mainwindow.cpp
+++ b/examples/serialbus/modbus/client/mainwindow.cpp
@@ -12,6 +12,8 @@
 #include <QStatusBar>
 #include <QUrl>
 
+using namespace Qt::StringLiterals;
+
 enum ModbusConnection {
     Serial,
     Tcp
@@ -51,11 +53,11 @@ MainWindow::MainWindow(QWidget *parent)
     ui->connectType->setEnabled(false);
 #endif
 
-    auto model = new QStandardItemModel(10, 1, this);
-    for (int i = 0; i < 10; ++i)
-        model->setItem(i, new QStandardItem(QStringLiteral("%1").arg(i + 1)));
+    auto *model = new QStandardItemModel(0, 1, this);
+    for (int i = 1; i <= 10; ++i)
+        model->appendRow(new QStandardItem(QString::number(i)));
     ui->writeSize->setModel(model);
-    ui->writeSize->setCurrentText("10");
+    ui->writeSize->setCurrentText(u"10"_s);
     connect(ui->writeSize, &QComboBox::currentTextChanged,
             writeModel, &WriteRegisterModel::setNumberOfValues);
 
@@ -152,28 +154,29 @@ void MainWindow::onConnectButtonClicked()
 
     statusBar()->clearMessage();
     if (modbusDevice->state() != QModbusDevice::ConnectedState) {
+        const auto settings = m_settingsDialog->settings();
         if (static_cast<ModbusConnection>(ui->connectType->currentIndex()) == Serial) {
             modbusDevice->setConnectionParameter(QModbusDevice::SerialPortNameParameter,
                 ui->portEdit->text());
 #if QT_CONFIG(modbus_serialport)
             modbusDevice->setConnectionParameter(QModbusDevice::SerialParityParameter,
-                m_settingsDialog->settings().parity);
+                settings.parity);
             modbusDevice->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,
-                m_settingsDialog->settings().baud);
+                settings.baud);
             modbusDevice->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,
-                m_settingsDialog->settings().dataBits);
+                settings.dataBits);
             modbusDevice->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,
-                m_settingsDialog->settings().stopBits);
+                settings.stopBits);
 #endif
         } else {
             const QUrl url = QUrl::fromUserInput(ui->portEdit->text());
             modbusDevice->setConnectionParameter(QModbusDevice::NetworkPortParameter, url.port());
             modbusDevice->setConnectionParameter(QModbusDevice::NetworkAddressParameter, url.host());
         }
-        modbusDevice->setTimeout(m_settingsDialog->settings().responseTime);
-        modbusDevice->setNumberOfRetries(m_settingsDialog->settings().numberOfRetries);
+        modbusDevice->setTimeout(settings.responseTime);
+        modbusDevice->setNumberOfRetries(settings.numberOfRetries);
         if (!modbusDevice->connectDevice()) {
-            statusBar()->showMessage(tr("Connect failed: ") + modbusDevice->errorString(), 5000);
+            statusBar()->showMessage(tr("Connect failed: %1").arg(modbusDevice->errorString()), 5000);
         } else {
             ui->actionConnect->setEnabled(false);
             ui->actionDisconnect->setEnabled(true);
@@ -210,7 +213,7 @@ void MainWindow::onReadButtonClicked()
         else
             delete reply; // broadcast replies return immediately
     } else {
-        statusBar()->showMessage(tr("Read error: ") + modbusDevice->errorString(), 5000);
+        statusBar()->showMessage(tr("Read error: %1").arg(modbusDevice->errorString()), 5000);
     }
 }
 
@@ -250,22 +253,24 @@ void MainWindow::onWriteButtonClicked()
     QModbusDataUnit writeUnit = writeRequest();
     QModbusDataUnit::RegisterType table = writeUnit.registerType();
     for (qsizetype i = 0, total = writeUnit.valueCount(); i < total; ++i) {
+        const auto addr = i + writeUnit.startAddress();
         if (table == QModbusDataUnit::Coils)
-            writeUnit.setValue(i, writeModel->m_coils[i + writeUnit.startAddress()]);
+            writeUnit.setValue(i, writeModel->m_coils[addr]);
         else
-            writeUnit.setValue(i, writeModel->m_holdingRegisters[i + writeUnit.startAddress()]);
+            writeUnit.setValue(i, writeModel->m_holdingRegisters[addr]);
     }
 
     if (auto *reply = modbusDevice->sendWriteRequest(writeUnit, ui->serverEdit->value())) {
         if (!reply->isFinished()) {
             connect(reply, &QModbusReply::finished, this, [this, reply]() {
-                if (reply->error() == QModbusDevice::ProtocolError) {
+                const auto error = reply->error();
+                if (error == QModbusDevice::ProtocolError) {
                     statusBar()->showMessage(tr("Write response error: %1 (Modbus exception: 0x%2)")
                         .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16),
                         5000);
-                } else if (reply->error() != QModbusDevice::NoError) {
+                } else if (error != QModbusDevice::NoError) {
                     statusBar()->showMessage(tr("Write response error: %1 (code: 0x%2)").
-                        arg(reply->errorString()).arg(reply->error(), -1, 16), 5000);
+                        arg(reply->errorString()).arg(error, -1, 16), 5000);
                 }
                 reply->deleteLater();
             });
@@ -274,7 +279,7 @@ void MainWindow::onWriteButtonClicked()
             reply->deleteLater();
         }
     } else {
-        statusBar()->showMessage(tr("Write error: ") + modbusDevice->errorString(), 5000);
+        statusBar()->showMessage(tr("Write error: %1").arg(modbusDevice->errorString()), 5000);
     }
 }
 
@@ -288,10 +293,11 @@ void MainWindow::onReadWriteButtonClicked()
     QModbusDataUnit writeUnit = writeRequest();
     QModbusDataUnit::RegisterType table = writeUnit.registerType();
     for (qsizetype i = 0, total = writeUnit.valueCount(); i < total; ++i) {
+        const auto addr = i + writeUnit.startAddress();
         if (table == QModbusDataUnit::Coils)
-            writeUnit.setValue(i, writeModel->m_coils[i + writeUnit.startAddress()]);
+            writeUnit.setValue(i, writeModel->m_coils[addr]);
         else
-            writeUnit.setValue(i, writeModel->m_holdingRegisters[i + writeUnit.startAddress()]);
+            writeUnit.setValue(i, writeModel->m_holdingRegisters[addr]);
     }
 
     if (auto *reply = modbusDevice->sendReadWriteRequest(readRequest(), writeUnit,
@@ -301,7 +307,7 @@ void MainWindow::onReadWriteButtonClicked()
         else
             delete reply; // broadcast replies return immediately
     } else {
-        statusBar()->showMessage(tr("Read error: ") + modbusDevice->errorString(), 5000);
+        statusBar()->showMessage(tr("Read error: %1").arg(modbusDevice->errorString()), 5000);
     }
 }
 
@@ -321,26 +327,26 @@ void MainWindow::onWriteTableChanged(int index)
 
 QModbusDataUnit MainWindow::readRequest() const
 {
-    const auto table =
-        static_cast<QModbusDataUnit::RegisterType>(ui->writeTable->currentData().toInt());
+    const auto table = ui->writeTable->currentData().value<QModbusDataUnit::RegisterType>();
 
     int startAddress = ui->readAddress->value();
     Q_ASSERT(startAddress >= 0 && startAddress < 10);
 
     // do not go beyond 10 entries
-    quint16 numberOfEntries = qMin(ui->readSize->currentText().toUShort(), quint16(10 - startAddress));
+    quint16 numberOfEntries = qMin(ui->readSize->currentText().toUShort(),
+                                   quint16(10 - startAddress));
     return QModbusDataUnit(table, startAddress, numberOfEntries);
 }
 
 QModbusDataUnit MainWindow::writeRequest() const
 {
-    const auto table =
-        static_cast<QModbusDataUnit::RegisterType>(ui->writeTable->currentData().toInt());
+    const auto table = ui->writeTable->currentData().value<QModbusDataUnit::RegisterType>();
 
     int startAddress = ui->writeAddress->value();
     Q_ASSERT(startAddress >= 0 && startAddress < 10);
 
     // do not go beyond 10 entries
-    quint16 numberOfEntries = qMin(ui->writeSize->currentText().toUShort(), quint16(10 - startAddress));
+    quint16 numberOfEntries = qMin(ui->writeSize->currentText().toUShort(),
+                                   quint16(10 - startAddress));
     return QModbusDataUnit(table, startAddress, numberOfEntries);
 }
diff --git a/examples/serialbus/modbus/client/mainwindow.h b/examples/serialbus/modbus/client/mainwindow.h
index f2ab08c..57d6e61 100644
--- a/examples/serialbus/modbus/client/mainwindow.h
+++ b/examples/serialbus/modbus/client/mainwindow.h
@@ -10,11 +10,9 @@
 QT_BEGIN_NAMESPACE
 
 class QModbusClient;
-class QModbusReply;
 
 namespace Ui {
 class MainWindow;
-class SettingsDialog;
 }
 
 QT_END_NAMESPACE
@@ -50,7 +48,6 @@ private slots:
 
 private:
     Ui::MainWindow *ui = nullptr;
-    QModbusReply *lastRequest = nullptr;
     QModbusClient *modbusDevice = nullptr;
     SettingsDialog *m_settingsDialog = nullptr;
     WriteRegisterModel *writeModel = nullptr;
diff --git a/examples/serialbus/modbus/client/writeregistermodel.cpp b/examples/serialbus/modbus/client/writeregistermodel.cpp
index 6cc62a5..de6ffbd 100644
--- a/examples/serialbus/modbus/client/writeregistermodel.cpp
+++ b/examples/serialbus/modbus/client/writeregistermodel.cpp
@@ -3,6 +3,8 @@
 
 #include "writeregistermodel.h"
 
+using namespace Qt::StringLiterals;
+
 enum { NumColumn = 0, CoilsColumn = 1, HoldingColumn = 2, ColumnCount = 3, RowCount = 10 };
 
 WriteRegisterModel::WriteRegisterModel(QObject *parent)
@@ -11,77 +13,81 @@ WriteRegisterModel::WriteRegisterModel(QObject *parent)
 {
 }
 
-int WriteRegisterModel::rowCount(const QModelIndex &/*parent*/) const
+int WriteRegisterModel::rowCount(const QModelIndex & /* parent */) const
 {
     return RowCount;
 }
 
-int WriteRegisterModel::columnCount(const QModelIndex &/*parent*/) const
+int WriteRegisterModel::columnCount(const QModelIndex & /* parent */) const
 {
     return ColumnCount;
 }
 
 QVariant WriteRegisterModel::data(const QModelIndex &index, int role) const
 {
-    if (!index.isValid() || index.row() >= RowCount || index.column() >= ColumnCount)
-        return QVariant();
+    const int row = index.row();
+    const int column = index.column();
+    if (!index.isValid() || row >= RowCount || column >= ColumnCount)
+        return {};
 
     Q_ASSERT(m_coils.count() == RowCount);
     Q_ASSERT(m_holdingRegisters.count() == RowCount);
 
-    if (index.column() == NumColumn && role == Qt::DisplayRole)
-        return QString::number(index.row());
+    if (column == NumColumn && role == Qt::DisplayRole)
+        return QString::number(row);
 
-    if (index.column() == CoilsColumn && role == Qt::CheckStateRole) // coils
-        return m_coils.at(index.row()) ? Qt::Checked : Qt::Unchecked;
+    if (column == CoilsColumn && role == Qt::CheckStateRole) // coils
+        return m_coils.at(row) ? Qt::Checked : Qt::Unchecked;
 
-    if (index.column() == HoldingColumn && role == Qt::DisplayRole) // holding registers
-        return QString("0x%1").arg(QString::number(m_holdingRegisters.at(index.row()), 16));
+    if (column == HoldingColumn && role == Qt::DisplayRole) // holding registers
+        return QString("0x%1").arg(QString::number(m_holdingRegisters.at(row), 16));
 
-    return QVariant();
+    return {};
 
 }
 
 QVariant WriteRegisterModel::headerData(int section, Qt::Orientation orientation, int role) const
 {
     if (role != Qt::DisplayRole)
-        return QVariant();
+        return {};
 
     if (orientation == Qt::Horizontal) {
         switch (section) {
         case NumColumn:
-            return QStringLiteral("#");
+            return u"#"_s;
         case CoilsColumn:
-            return QStringLiteral("Coils  ");
+            return u"Coils  "_s;
         case HoldingColumn:
-            return QStringLiteral("Holding Registers");
+            return u"Holding Registers"_s;
         default:
             break;
         }
     }
-    return QVariant();
+    return {};
 }
 
 bool WriteRegisterModel::setData(const QModelIndex &index, const QVariant &value, int role)
 {
-    if (!index.isValid() ||  index.row() >= RowCount || index.column() >= ColumnCount)
+    const int row = index.row();
+    const int column = index.column();
+    if (!index.isValid() ||  row >= RowCount || column >= ColumnCount)
         return false;
 
     Q_ASSERT(m_coils.count() == RowCount);
     Q_ASSERT(m_holdingRegisters.count() == RowCount);
 
-    if (index.column() == CoilsColumn && role == Qt::CheckStateRole) { // coils
+    if (column == CoilsColumn && role == Qt::CheckStateRole) { // coils
         auto s = static_cast<Qt::CheckState>(value.toUInt());
-        s == Qt::Checked ? m_coils.setBit(index.row()) : m_coils.clearBit(index.row());
+        s == Qt::Checked ? m_coils.setBit(row) : m_coils.clearBit(row);
         emit dataChanged(index, index);
         return true;
     }
 
-    if (index.column() == HoldingColumn && role == Qt::EditRole) { // holding registers
+    if (column == HoldingColumn && role == Qt::EditRole) { // holding registers
         bool result = false;
         quint16 newValue = value.toString().toUShort(&result, 16);
         if (result)
-            m_holdingRegisters[index.row()] = newValue;
+            m_holdingRegisters[row] = newValue;
 
         emit dataChanged(index, index);
         return result;
@@ -92,16 +98,18 @@ bool WriteRegisterModel::setData(const QModelIndex &index, const QVariant &value
 
 Qt::ItemFlags WriteRegisterModel::flags(const QModelIndex &index) const
 {
-    if (!index.isValid() || index.row() >= RowCount || index.column() >= ColumnCount)
-        return QAbstractTableModel::flags(index);
-
+    const int row = index.row();
+    const int column = index.column();
     Qt::ItemFlags flags = QAbstractTableModel::flags(index);
-    if ((index.row() < m_address) || (index.row() >= (m_address + m_number)))
+    if (!index.isValid() || row >= RowCount || column >= ColumnCount)
+        return flags;
+
+    if ((row < m_address) || (row >= (m_address + m_number)))
         flags &= ~Qt::ItemIsEnabled;
 
-    if (index.column() == CoilsColumn) // coils
+    if (column == CoilsColumn) // coils
         return flags | Qt::ItemIsUserCheckable;
-    if (index.column() == HoldingColumn) // holding registers
+    if (column == HoldingColumn) // holding registers
         return flags | Qt::ItemIsEditable;
 
     return flags;