error C2976: 'QMap' : too few template arguments in QMetaObject::invokeMethod

Question

i tryt to invoke QMetaObject::invokeMethod from object to the caller object i have this from the object :

bool bReturnInvokeMethod = false;
bool bInvokeMethod1= QMetaObject::invokeMethod(m_pCollector,
                            "setStack",
                            Qt::BlockingQueuedConnection,
                            Q_ARG(QMap<QString,QVector<std::string > >, linksQTResultMap));

but im getting this error:

error C2976: 'QMap' : too few template arguments

why its well defined type

Answer 1

The problem is that the C++ preprocessor isn't aware of templates, and Q_ARG is a macro.

When the preprocessor sees:

Q_MAP(foo<bar,baz>,blop)

It's interpreted as a three distinct arguments (quotes to make it more visible):

Q_MAP( "foo<bar" , "baz>" , "blop" )

and the resulting expansion doesn't make sense.

Something that usually works to counter this is to use a typedef:

typedef QMap<QString,QVector<std::string> > MyStringVectorMap;
...
Q_MAP(MyStringVectorMap, linksQTResultMap)
...