QSignalMapper is deprecated
今天参考 qt4 的书籍，在 qt5 的平台上面，用了 QSignalMapper，结果收到警告“ QSignalMapper is deprecated"。
经过一番查找，找到了相应的说明, 参考自：https://doc.qt.io/qt-5/qsignalmapper.html This class is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code. 官方建议 qt5 里面使用 lambda 方式表达。
下面是旧的方式:
class ButtonWidget : public QWidget
{
Q_OBJECT
public:
ButtonWidget(const QStringList &texts, QWidget *parent = 0);
signals:
void clicked(const QString &text);
private:
QSignalMapper *signalMapper;
};ButtonWidget::ButtonWidget(const QStringList &texts, QWidget *parent)
: QWidget(parent)
{
signalMapper = new QSignalMapper(this);
QGridLayout *gridLayout = new QGridLayout;
for (int i = 0; i < texts.size(); ++i) {
QPushButton *button = new QPushButton(texts[i]);
connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));
signalMapper->setMapping(button, texts[i]);
gridLayout->addWidget(button, i / 3, i % 3);
}
connect(signalMapper, SIGNAL(mapped(QString)),
this, SIGNAL(clicked(QString)));
setLayout(gridLayout);
}This class was mostly useful before lambda functions could be used as slots. The example above can be rewritten simpler without QSignalMapper by connecting to a lambda function. 下面是新的方式：
ButtonWidget::ButtonWidget(const QStringList &texts, QWidget *parent)
: QWidget(parent)
{
QGridLayout *gridLayout = new QGridLayout;
for (int i = 0; i < texts.size(); ++i) {
QString text = texts[i];
QPushButton *button = new QPushButton(text);
connect(button, &QPushButton::clicked, [=] { clicked(text); });
gridLayout->addWidget(button, i / 3, i % 3);
}
setLayout(gridLayout);
}