Question

I have the following outline of a Python program (using PyQt4):

class Polygon( QtGui.QGraphicsItem ):

    def __init__(self):
        super(Polygon, self).__init__()

    def addpoint( self, point ):
        if last_point: 
            # trying to add auto-save here

class MainWidget(QtGui.QWidget):

    openFileName = ""
    list_of_polygons = []

    def __init__(self):
        super(MainWidget, self).__init__()

    def openFile( self ):
        call dialog
        self.openFileName = ...

    def saveFile( self ):
        # needs to access a couple something with self.variables, like self.openFileName


def main():

    app = QtGui.QApplication(sys.argv)
    ex = MainWidget()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Functionality is an image viewer where I’m creating polygons to tag object. I’d like to call an auto-save once a polygon has been created.

So for saving a polygon I need to call it from the saveFile function MainWidget class. My problem is that the saving functionality is implemented in the MainWidget class, and I don’t know how to access them from inside the Polygon class.

What would be the best idea to do this? Should I make saveFile global? If yes, then how do I access the self. variables of the MainWidget?

Answer 1

You probably need to pass the widget object to the Polygon when you create it so that it knows what its “parent” widget object is:

class Polygon( QtGui.QGraphicsItem ):

    def __init__(self, parent):
        self.parent = parent
        # ...

(and then foo = Polygon(your_widget) when you create it).

---

Then you can just call self.parent.saveFile(...) or whatnot.