Workflow selection - UI breaks after closing a workflow about napari-allencell-segmenter

[schoinh]

Traceback:

~/Projects/napari-aicssegmentation/napari_aicssegmentation/controller/workflow_select_controller.py in _handle_layers_change(self=<napari_aicssegmentation.controller.workflow_select_controller.WorkflowSelectController object>, e=<Event blocked=False handled=False native=None source=None sources=[] type=layers_change>)
    106         """
    107         self.model.layers = self._get_3D_layers()
--> 108         self._view.update_layers(self.model.layers, self.model.selected_layer)
        self._view.update_layers = <bound method WorkflowSelectView.update_layers of <napari_aicssegmentation.view.workflow_select_view.WorkflowSelectView object at 0x7f95f8b28040>>
        self.model.layers = ['test_sample_single', '0. test_sample_single: ch[0] actb', '0. 0. test_sample_single: ch[0] actb: ch[0] actb']
        self.model.selected_layer = <Image layer '0. test_sample_single: ch[0] actb' at 0x7f95e8fa6f70>
    109 
    110         if self.model.selected_layer is None or self.model.selected_layer.name not in self.model.layers:

~/Projects/napari-aicssegmentation/napari_aicssegmentation/view/workflow_select_view.py in update_layers(self=<napari_aicssegmentation.view.workflow_select_view.WorkflowSelectView object>, layers=['test_sample_single', '0. test_sample_single: ch[0] actb', '0. 0. test_sample_single: ch[0] actb: ch[0] actb'], selected_layer=<Image layer '0. test_sample_single: ch[0] actb'>)
     97         pyqtRemoveInputHook()
     98         pdb.set_trace()
---> 99         self._reset_combo_box(self.combo_layers)
        self._reset_combo_box = <bound method WorkflowSelectView._reset_combo_box of <napari_aicssegmentation.view.workflow_select_view.WorkflowSelectView object at 0x7f95f8b28040>>
        self.combo_layers = <PyQt5.QtWidgets.QComboBox object at 0x7f95f8b28670>
    100 
    101         if layers is None or len(layers) == 0:

~/Projects/napari-aicssegmentation/napari_aicssegmentation/view/workflow_select_view.py in _reset_combo_box(self=<napari_aicssegmentation.view.workflow_select_view.WorkflowSelectView object>, combo=<PyQt5.QtWidgets.QComboBox object>)
    158         Reset a combo box to its original state, keeping the header but removing all other items
    159         """
--> 160         if combo.count() > 0:
        combo.count = <built-in method count of QComboBox object at 0x7f95f8b28670>
    161             header = combo.itemText(0)
    162             combo.clear()

RuntimeError: wrapped C/C++ object of type QComboBox has been deleted

I looked into this and it might not be a quick fix… I think it may have to do with Qt garbage collection, and also found someone else who seemed to be having the same kind of issue on Zulip while developing their own layer manager.

Also a similar-sounding problem in the napari repo: napari/napari#2238

[schoinh]

Here's something that looks like it could be a very helpful explanation: http://enki-editor.org/2014/08/23/Pyqt_mem_mgmt.html (I haven't had a chance to read it thoroughly / apply its wisdoms yet)