How we can connect the signals and slot with different arguments?

Question

In Qt, signals and slots require matching argument types:

QObject::connect: Incompatible sender/receiver arguments QLabel::linkActivated(QString) --> Butt

Answer 1

As a complementary answer, if you don't want to write an intermediate slot, you can use the lambda expressions (of course with C++11 support) to invoke the method. However, the connector class must know the parameter types used in those particular signals and slots.

To give an example, assuming that you're trying to connect a signal with a parameter type of QString to a slot with a parameter type of char, you can do it like this;

class SignalClass{
signals:
    void testSignal(QString tString);
};

class SlotClass{
public slots:
    void testSlot(char tChar);
};

class ConnectorClass{
public:
    void connectSignalAndSlot () {
        SignalClass tSigClass;
        SlotClass tSlotClass;
        connect(&tSigClass, &SignalClass::testSignal,
                [=](QString tString) { this->metaObject()->invokeMethod(tSlotClass,"testSlot", Q_ARG(char, tString.at(0).toLatin1())) }
        );
    }
}

Kinda ugly stuff, but does the job.

• No coupled classes
• No intermediate connector functions