The dataChanged Signal Not Performing as Expected

[ChristianEhrlicher]

There must be another reason - from the C++ side it doesn't matter - see https://en.cppreference.com/w/cpp/la...ault_arguments or a good C++ book.

[Corny]

I don't disagree, that in C++ that's the way it works. However I am at a loss understanding what exactly is happening here. I am simply attempting to let anyone else who may run into a similar circumstance, know how I resolved the situation.

[d_stranz]

I don't disagree, that in C++ that's the way it works.

As Christian points out, there is absolutely no difference between emitting dataChanged() with two arguments vs. with a third argument being an empty (but explicitly declared) QVector<int>(). Both versions should compile to exactly the same thing (with the compiler inserting the default argument in the first instance), so there is absolutely no way that a slot receiving the signal can tell how it was called in the source code. If you are seeing a difference in behavior if you build and run code written first one way and then the other with no other code changes and exactly the same runtime test conditions then I would also be at a loss to explain why.