Qt的新信号/时隙语法问题 - 连接到一个简单的函数

Question

如下所述：，您可以将信号连接到一个简单的函数，如下所示：

connect(
sender, &Sender::valueChanged,
someFunction
);

这是我的程序：

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>

void handleReply(QNetworkReply *reply)
{
QString replyStr = reply->readAll();
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QNetworkAccessManager manager;
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
return a.exec();
}

但是我得到一些错误：

main.cpp:18: error: call to non-static member function without an object argument
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
main.cpp:18: error: 'QNetworkReply' does not refer to a value
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
^
main.cpp:18: error: expected expression
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
^
main.cpp:18: error: 'QNetworkReply' does not refer to a value
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
              ^
/usr/include/x86_64-linux-gnu/qt5/QtNetwork/qnetworkreply.h:62: declared here
class Q_NETWORK_EXPORT QNetworkReply: public QIODevice
main.cpp:18: error: expected expression
connect(&manager, &QNetworkAccessManager::finished(QNetworkReply*), handleReply(QNetworkReply*));
                            ^
^

我将不胜感激任何帮助。谢谢。

Answer 1

当您使用新的连接语法时，无需指示参数的类型，因此只需使用：

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QDebug>
static void handleReply(QNetworkReply *reply)
{
QString replyStr = reply->readAll();
// do stuff
qDebug()<< replyStr;
reply->deleteLater();
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QNetworkAccessManager manager;
QObject::connect(&manager, &QNetworkAccessManager::finished, &handleReply);
manager.get(QNetworkRequest(QUrl("https://www.google.com")));
return a.exec();
}

注意：只有在继承自QObject的类中时才应使用connect(...)，在main的情况下应使用QObject::connect(...)