c++ - 如何在 QSignalSpy 上使用 foreach 循环

Question

如何foreach在 a 上使用循环QSignalSpy？

这就是我想要做的：

foreach( const QList<QVariant> &args, mySignalSpy )
{
    Q_ASSERT( args.count() == 2 );
    QVariant arg0 = args[0];
    QVariant arg1 = args[1];
    doSomething( arg0, arg1 );
}

这是我得到的错误：

/usr/local/Trolltech/Qt-4.8.2-shared/include/QtTest/qsignalspy.h: In instantiation of ‘QForeachContainer<T>::QForeachContainer(const T&) [with T = QSignalSpy]’:
MyTester.cxx:843:64:   required from here
/usr/local/Trolltech/Qt-4.8.2-shared/include/QtCore/qobject.h:333:5: error: ‘QObject::QObject(const QObject&)’ is private

Answer 1

foreach makes a copy of passed container. QSignalSpy inherits QObject hence it cannot be copied. These two facts cause the error.

The simpliest workaround is to use usual for loop. You can also create a non-QObject copy of the list and use it to iterate:

QList< QList<QVariant> > list = mySignalSpy;
foreach( const QList<QVariant> &args, list ) {
  //...
}