I edited the title to be more specific (and accurate) and tweaked example to show difference between supplying column definitions and not. Also updated the TryCF example.
this is not a member function, this is a method of the QueryImpl class, more percise a method defined by this interface:
So this is not offical functionality, of course we can talk about adding an offical isEmpty function, but the behaviour of this method cannot be changed.
You are right, the IsEmpty(query) function works fine.
But why is the iterator not empty in the first place?
we will add a member function for this ans also to other types