Reverse QMetaMethod::fromSignal() - c++

Question

I already have a working connection from SomeClass::somSignal using the SIGNAL() macro but I don't have a way of connecting it to a lambda using &SomeClass::someSignal mostly because someClass is inaccessible. I have the QObject *, though.
I tried to look into QMetaObject; it should have some sort of look-up structure where these details are kept.
We can have:
QMetaMethod::fromSignal(PointerToMemberFunction)
returning QMetaMethod
My question is, is it possible to have something like this?
fromMetaMethod(QMetaMethod)
returning PointerToMemberFunction
??
Thanks.

Answer 1

One way to create the connection you want does not require you to find any methods address.Simply:
Create a signal-to-signal connection, from SomeClass::someSignal to your own signal in your own class using the SIGNAL() connection style.
Connect your signal to the lambda.
You only have to make sure the parameters of the original signal are forwarded to your lambda.
Example:
QObject::connect(
pointerToSomeClass, SIGNAL(someSignal(int)),
pointerToMyClass , SIGNAL(mySignal(int)),
Qt::DirectConnection
);
QObject::connect(
pointerToMyClass, &MyClass::mySignal,
[](int i) { ... }
);
If you happen to need the sender of the original signal, then you will need a slot.
Example:
void myClass::mySlot(int i)
{
emit mySignal(sender(), i);
}
and
QObject::connect(
pointerToSomeClass, SIGNAL(someSignal(int)),
pointerToMyClass , SIGNAL(mySlot(int)),
Qt::DirectConnection
);
QObject::connect(
pointerToMyClass, &MyClass::mySignal,
[](QObject* sender, int i) { ... }
);