Question

I made a new class named PageRangeListWidgetItem which inherits from QListWidgetItem

class PageRangeListWidgetItem : public QListWidgetItem
{
    ...
    private:
        int start, end;

        bool operator<(const PageRangeListWidgetItem &other) const {
            if (start == other.start)
                return end < other.end;
            return start < other.start;
        }
};

and these items are being added to a QListWidget through user input. The QListWidget contains only these PageRangeListWidgetItem’s, so I hoped that by calling the sortItems() function of the QListWidget, that it would use the overloaded operator< to sort the items to my liking, but unfortunately it doesn’t, it keeps on sorting the list as if it contained pure QListWidgetItems.

How can I change this behaviour? Do I have to create a custom QListWidget class or is there an easier way?

Answer 1

The < function that is called by Qt’s framework is

virtual bool operator<(const QListWidgetItem &other) const

The one you have defined does not match this function signature (PageRangeListWidgetItem instead of QListWidgetItem), and thus does not override the virtual function and doesn’t get called.

You need to write a < function that takes in a QListWidgetItem and uses that object to sort rather than your custom object.