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  1. Qt for Python
  2. PYSIDE-671

QGraphicsItem.parentItem() fails when parent has __getitem__ defined



    • Type: Bug
    • Status: Reported
    • Priority: P3: Somewhat important
    • Resolution: Unresolved
    • Affects Version/s: 5.9
    • Fix Version/s: None
    • Component/s: PySide
    • Labels:
    • Environment:
      ubuntu 17.10 + anaconda + PySide wheel 5.9.0a1.dev1525349078


      When using subclasses of QGraphicsItem, I have found that defining _getitem_ on a subclass will cause parentItem() to fail on a child item. For example:


      from PySide2.QtWidgets import QGraphicsItem, QGraphicsRectItem
      class GraphicsItem(QGraphicsItem):
          def __getitem__(self, item):
              return None
      parent = GraphicsItem()
      child = QGraphicsRectItem(parent)
      print("Parent:", child.parentItem())

      Running the above code generates the following error:


      Traceback (most recent call last):
        File "<stdin>", line 1, in <module>
      TypeError: object of type 'GraphicsItem' has no len()

      The above example might seem contrived, but it was the result of about an hour of stripping down a larger application until it became clear what the problem was. So although the solution here is simple (remove _getattr_ from parent class), it is not at all obvious when this is encountered in a real application, and the result is very difficult to debug.


        For Gerrit Dashboard: PYSIDE-671
        # Subject Branch Project Status CR V



            • Assignee:
              crmaurei Cristian Maureira-Fredes
              lcampagn Luke
            • Votes:
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              • Created:

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