2

根据 QT5 文档，QRadioButton 继承了 QAbstractButton 的 4 个信号，其中包括clicked信号。它的模板clicked(bool checked = false)让我很困惑为什么这段代码会返回一个很长的错误消息，其中一部分是error: static assertion failed: Signal and slot arguments are not compatible.

代码（简化，可能包含不属于原件的错误）：

#include <QApplication>
#include <QMainWindow>
#include <QRadioButton>

#include <iostream>

class front_end : public QWidget
{
  Q_OBJECT

public:
  void load()
  {
    auto *rbtn_0 = new QRadioButton(tr("Reference"), this);
    rbtn_0->setChecked(true);

    QObject::connect(rbtn_0, &QRadioButton::clicked, this, SLOT(rbtn_toggle(bool)));
  }

public slots:
  void rbtn_toggle(bool arg_0)
  {
    std::cout << "Toggle\n";
  }
};

int main(int argc, char *argv[]) {
  QApplication app(argc, argv);

  front_end FrontEnd;
  FrontEnd.load();

  return app.exec();
}

编译：

qmake -project -norecursive -Wall -Wparser -o main.pro;
echo "QT += widgets" >> main.pro;
echo "CONFIG += c++11" >> main.pro;

qmake -norecursive main.pro;
make;

错误信息：

g++ -c -m64 -pipe -O2 -std=c++0x -Wall -W -D_REENTRANT -fPIE -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++-64 -I. -I. -I/usr/include/qt5 -I/usr/include/qt5/QtWidgets -I/usr/include/qt5/QtGui -I/usr/include/qt5/QtCore -I. -o main.o main.cpp
main.cpp:21:8: warning: unused parameter ‘arg_0’ [-Wunused-parameter]
   void rbtn_toggle(bool arg_0)
        ^
In file included from /usr/include/qt5/QtCore/qcoreapplication.h:48:0,
                 from /usr/include/qt5/QtWidgets/qapplication.h:45,
                 from /usr/include/qt5/QtWidgets/QApplication:1,
                 from main.cpp:1:
/usr/include/qt5/QtCore/qobject.h: In instantiation of ‘static typename QtPrivate::QEnableIf<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == (-1)), QMetaObject::Connection>::Type QObject::connect(const typename QtPrivate::FunctionPointer<Func>::Object*, Func1, const QObject*, Func2, Qt::ConnectionType) [with Func1 = void (QAbstractButton::*)(bool); Func2 = const char*; typename QtPrivate::QEnableIf<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == (-1)), QMetaObject::Connection>::Type = QMetaObject::Connection; typename QtPrivate::FunctionPointer<Func>::Object = QAbstractButton]’:
main.cpp:17:83:   required from here
/usr/include/qt5/QtCore/qobject.h:300:122: warning: overflow in implicit constant conversion [-Woverflow]
         const int FunctorArgumentCount = QtPrivate::ComputeFunctorArgumentCount<Func2 , typename SignalType::Arguments>::Value;
                                                                                                                          ^
In file included from /usr/include/qt5/QtCore/qcoreapplication.h:45:0,
                 from /usr/include/qt5/QtWidgets/qapplication.h:45,
                 from /usr/include/qt5/QtWidgets/QApplication:1,
                 from main.cpp:1:
/usr/include/qt5/QtCore/qglobal.h:669:47: error: static assertion failed: Signal and slot arguments are not compatible.
 #define Q_STATIC_ASSERT_X(Condition, Message) static_assert(bool(Condition), Message)
                                               ^
/usr/include/qt5/QtCore/qobject.h:302:9: note: in expansion of macro ‘Q_STATIC_ASSERT_X’
         Q_STATIC_ASSERT_X((FunctorArgumentCount >= 0),
         ^
In file included from /usr/include/qt5/QtCore/qobjectdefs.h:47:0,
                 from /usr/include/qt5/QtCore/qobject.h:48,
                 from /usr/include/qt5/QtCore/qcoreapplication.h:48,
                 from /usr/include/qt5/QtWidgets/qapplication.h:45,
                 from /usr/include/qt5/QtWidgets/QApplication:1,
                 from main.cpp:1:
/usr/include/qt5/QtCore/qobjectdefs_impl.h: In instantiation of ‘struct QtPrivate::FunctorReturnType<const char*, QtPrivate::List<> >’:
/usr/include/qt5/QtCore/qobject.h:305:158:   required from ‘static typename QtPrivate::QEnableIf<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == (-1)), QMetaObject::Connection>::Type QObject::connect(const typename QtPrivate::FunctionPointer<Func>::Object*, Func1, const QObject*, Func2, Qt::ConnectionType) [with Func1 = void (QAbstractButton::*)(bool); Func2 = const char*; typename QtPrivate::QEnableIf<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == (-1)), QMetaObject::Connection>::Type = QMetaObject::Connection; typename QtPrivate::FunctionPointer<Func>::Object = QAbstractButton]’
main.cpp:17:83:   required from here
/usr/include/qt5/QtCore/qobjectdefs_impl.h:633:78: error: request for member ‘operator()’ in ‘QtPrivate::FunctorReturnType<Functor, QtPrivate::List<Tail ...> >::dummy<const char*>()’, which is of non-class type ‘const char*’
         typedef decltype(dummy<Functor>().operator()((dummy<ArgList>())...)) Value;

编辑：

是的，我知道将信号语法更改为 QT4 标准“SIGNAL(clicked(bool))”会解决它，但我正试图摆脱这种语法，更重要的是，了解问题所在。

4

2 回答 2

4

您正在混合旧语法和新语法。每次通话选择一个来连接/断开连接。对于重载的信号/槽，您需要将函数指针转换为正确的类型以防新语法

于 2016-08-07T20:35:33.690 回答
0

我在 stackoverflow 上搜索了此类问题，但没有找到任何东西，直到 Silicomancer 向我指出了一篇非常出色的帖子——第 5 部分/第 5 条。

读完后，解决方案很简单：

QObject::connect(rbtn_0, &QRadioButton::clicked, this, &front_end::rbtn_toggle);
于 2016-08-07T21:41:34.217 回答