Connect signal to slot with derived parameter

How to use signals and slots in Slicer 3d? qt connect signal to slot with parameter From Qt onwards, Qt offers two different ways to write signal-slot connections in C++: The string-based connection syntax and the functor-based qt slot signal By the way, it doesn't matter whether we specify the argument in a connect call as const Copy& or Copy Qt normalises the type to Copy any way

qt signal slot I am seeing connect() with 3 or 4 parameters It looks like the rule is that with 4 parameters, we can get the required type of the 2nd