FWD » Core Development » User Interface

Starting from trunk rev. 14821, there has been a regression with setting SCREEN-VALUE to a SELECTION-LIST. From my investigations, this could have potentially happened to EDITOR and TOGGLE-BOX too.

A small example that raises the error ** Attribute SCREEN-VALUE for the SELECTION-LIST <name> has an invalid value of . (4058) is:

define variable sl as character 
  view-as selection-list
  list-item-pairs "A", "A", "B", "B" 
  size 20 by 20.

define frame f-main sl.
enable all with frame f-main.
do with frame f-main:
    sl:SCREEN-VALUE = "".
    message sl:SCREEN-VALUE.
end.

When working with a SELECTION-LIST, if one tries to set the "" value to the widget, the program actually treats that value as ?. Thus, the correct output of this example is ? and no errors should be raised.

When doing the changes from trunk 14821 and 14830, I managed to disrupt the workflow of the program when handling a few setScreenValue functions. Because I added another GenericWidget.setScreenValue function, this time with 4 parameters, the call of widget.setScreenValue from GenericFrame.setScreenValue changed from 3 arguments given to 4. This is important when considering the following flow:

• Before any of my changes:
  • widget.setScreenValue(3 arguments) inside GenericFrame -> SelectionList.setScreenValue(3 parameters) -> ControlSetEntity.setScreenValue(3 parameters) if super is called (in this case it is not, but it could appear in other widgets).
• With the changes, widget.setScreenValue(3 arguments) became widget.setScreenValue(4 arguments), and ControlSetEntity.setScreenValue(3 parameters) became ControlSetEntity.setScreenValue(4 parameters).
• After the changes:
  • widget.setScreenValue(4 arguments) inside GenericFrame -> ControlSetEntity.setScreenValue(4 parameters)
  • Note that SelectionList.setScreenValue(3 parameters) is skipped because I forgot to update the function so that it uses 4 parameters. This resulted in some validations being left behind and not being called at all.

This might have happened for EditorWidget and ToggleBoxWidget too as I noticed that I did not do any updates there. I'll post a patch here and wait for some feedback. Also, both the example from #8239-1 and the test from a large customer application work well with the patch.