Recursion while using QTreeWidgetItem.__lt__

Bluebird75

Hi,

I want to provide a custom sort order for QTreeWidgetItems withing the QTreeWidget.

According to documentation, I can use the lt method: https://doc.qt.io/qtforpython-5/PySide2/QtWidgets/QListWidgetItem.html#PySide2.QtWidgets.PySide2.QtWidgets.QListWidgetItem.lt

However, in practice, this gets a bit more complicated than this:

Here is my code :

class RepoBranchInfoTreeItem(QTreeWidgetItem):

    def __lt__(self, other: 'QTreeWidgetItem') -> bool:
        col = self.treeWidget().sortColumn()
        if col != 1:
            # regular sorting
            return bool( QTreeWidgetItem.__lt__(self, other) )

        colTextSelf = self.text(col)
        colTextOther = other.text(col)
        if len(colTextSelf) and len(colTextOther) and colTextSelf[0].isdigit() and colTextOther[0].isdigit():
            # natural number sorting if we can
            return extractInt(colTextSelf) < extractInt(colTextOther)

        # regular sort strategy will compare strings and place all number starting strings before others
        return bool( super().__lt__(other) )

It's pretty simple, the idea is to use a natural sort order on column 1, if column 1 content is only made of digits.

The issue I have is the following :

Traceback (most recent call last):
  File "C:\work\Multigit\Dev\src\mg_dialog_git_switch_delete_branch.py", line 111, in __lt__
    def __lt__(self, other: 'QTreeWidgetItem') -> bool:
RecursionError: maximum recursion depth exceeded while calling a Python object

It seems that eventhough I call super().lt(self, other) or QTreeWidgetitem.lt(self, other), instead of calling the lt of QTreeWidgetItem , I end up calling my own method.

So, virtual method override seems to be broken, I can no longer call the parent method. Or rather, i call it but it eventually calls my own implementation.

Does anybody knows a way around this ?

By the way, it works in PyQt5

JonB

@Bluebird75
I would use either one of QTreeWidgetItem.__lt__(self, other) or super().__lt__(other), not both mixed. Maybe to rule out super() just QTreeWidgetItem.__lt__(self, other).

If what you say is so, surely you can remove most of your code and try one or other of:

    def __lt__(self, other: 'QTreeWidgetItem') -> bool:
        return bool( QTreeWidgetItem.__lt__(self, other) )
        # or next line
        # return bool( super().__lt__(other) )

and reproduce the problem.

By the way, it works in PyQt5

If code works in PyQt5 but not in PySide2 you can report it as a bug.

Bluebird75

I tried to use either super().__lt__ or QTreeWidgetItem.__lt__ with equivalent results. I suppose it is something due to the virtual overloading machineray that always picks up the python method in every case.

I got around it by simply not relying on the QTreeWidgetItem.__lt__ at all. I just do a regular string comparison and it works fine.

Final code looks like :

class RepoBranchInfoTreeItem(QTreeWidgetItem):
    
        def __lt__(self, other: 'QTreeWidgetItem') -> bool:
            col = self.treeWidget().sortColumn()
            if col != 1:
                # regular sorting
                return istrcmp(self.text(col), other.text(col))
    
            colTextSelf = self.text(col)
            colTextOther = other.text(col)
            if len(colTextSelf) and len(colTextOther) and colTextSelf[0].isdigit() and colTextOther[0].isdigit():
                # natural number sorting if we can
                return extractInt(colTextSelf) < extractInt(colTextOther)
    
            # regular sort strategy will compare strings and place all number starting strings before others
            return istrcmp(self.text(col), other.text(col))


def istrcmp(s1: str, s2: str) -> bool:
    '''Case-insensitive string compare'''
    return s1.lower() < s2.lower()

    ```

ctismer

Weird that this works with PyQt5. So we must try harder :^)

friedemannkleint

See PYSIDE-1951