Utilizing connect with the SIGNAL macro and a functor

VanDriekenof

Hello,

I'm trying to dynamically connect a widget to a functor. I have a file that contains the signature of the signal that I want to connect, as well as some info concerning what it should do, something along the line of:

"widget": "power_button",
"signal": "toggled(bool)",
"action": "power"

As you can see, the signal is easy to connect, I can just call connect with the string (I just have to prepend a "2" and convert to const char*). I can't (at least easily) use the pointer-to-member syntax easily because those widgets are created at runtime and they don't have all the same signals (and signal signatures).

So I would like to be able to call something like

QObject::connect(widget, signal_string, [](bool a){ set("power", a); });

but there is no connect overload like that, and I'm afraid the two syntaxes are fundamentally incompatible.

Is there a way to do what I want, or will I have to do something a bit more complicated ?

Thnaks a lot !

mrjj

Hi and welcome to the forums.
Sadly, macro syntax and lambdas cannot be mixed.
https://wiki.qt.io/New_Signal_Slot_Syntax
So I guess you are looking at something "bit more complicated "

raven-worx

@VanDriekenof
i once wrote an utility class for this

#include <functional>

typedef std::function<void()> LamdbaFunc;

class LambdaConnector : public QObject
{
    Q_OBJECT

public:
    LambdaConnector( QObject* obj, const char* signal, LambdaFunc functor ) : QObject(obj) {
        static QMetaMethod slotMethod;
        if( !slotMethod.isValid() )
        {
                const QMetaObject * mo = this->metaObject();
                int idx = mo->indexOfSlot("onEmit()");
                slotMethod = mo->method(idx);
        }

        QMetaMethod signalMethod = obj->metaObject()->method(obj->metaObject()->indexOfSignal(signal));
        connect( object, signalMethod, this, slotMethod );
   }

private slots:
    void onEmit() {
       m_SlotFunction();
   }

private:
    LambdaFunc m_SlotFunction;
};

Usage:

new LambdaConnector(obj, "signal()", [obj]() {
    obj->...
});
// or
new LambdaConnector(obj, QMetaObject::normalizedType("signal()").constData(), [obj]() {
    obj->...
});