Qt5 new signals-slots syntax does not work [SOLVED]

anaksimandr

Why this works
@connect(cmbList1, SIGNAL(currentIndexChanged(const QString&)),this, SLOT(func1(const QString&)));@

but this does not?
@connect(cmbList1, &QComboBox::currentIndexChanged, this, &MyClass::func1);@

log
error: C2664: 'QMetaObject::Connection QObject::connect(const QObject *,const char *,const QObject *,const char *,Qt::ConnectionType)' : cannot convert parameter 2 from 'overloaded-function' to 'const char *'
Context does not allow for disambiguation of overloaded function

lgeyer

Are you sure you are using Qt5 (and not Qt4)?

anaksimandr

yes. at other place this method works

cincirin

Note that QComboBox::currentIndexChanged has two signals. Compiler don't know what signal do you want. Need to explicitly tell the compiler correct functions address.

edit: for example for signal with QString argument, you need something like this:
@
void (QComboBox:: *indexChangedSignal)(QString) = &QComboBox::currentIndexChanged;
connect(comboBox, indexChangedSignal, this, &MyClass::func1)
@

anaksimandr

when i tried to compile code above i have this
error: C2440: 'initializing' : cannot convert from 'overloaded-function' to 'void (__thiscall QComboBox::* )(QString)'
None of the functions with this name in scope match the target type

anaksimandr

@connect(cmbProfiles, SIGNAL(currentIndexChanged(const QString&)),
this, SLOT(loadProfilesDetails(const QString&)));@
And now I see that in qt5 this code does not work too, it compiles but does not work. Sorry for my inattention.

anaksimandr

So now I must ask how to connect func to signal QComboBox::currentIndexChanged(const QString & text) in Qt5 ?

lgeyer

As cincirin already mentioned you will have to explicitly cast overloaded signals when using the function pointer syntax.

connect(cmbProfiles,
        static_cast<void (QComboBox::*)(const QString &)>(&QComboBox::currentIndexChanged), 
        this,
        &MyClass::loadProfilesDetails);

The equivalent of the string-based syntax is

connect(cmbProfiles, 
        SIGNAL(currentIndexChanged(const QString &)),
        this,
        SLOT(loadProfilesDetails(const QString &)));

or

connect(cmbProfiles, 
        SIGNAL(currentIndexChanged(QString)),
        this,
        SLOT(loadProfilesDetails(QString)));

anaksimandr

It works, thanks to all.

Ph0t0n

Wow... it works, but that is really ugly!

j-hap

I know this is quite old, but if someone ends up here again, this is the up-to-date way of defining an overload when connecting an overloaded signal: QOverload<int>::of(&QComboBox::currentIndexChanged)