Hello List!
I see the following code snippet in some Qt documentation:
QGraphicsScene scene;
scene.addText("Hello, world!");
QGraphicsView view(&scene);
view.show();
(From http://doc.qt.nokia.com/4.7-snapshot/qgraphicsview.html)
Both scene and view are automatic variables. If this example were
taken literally, would it lead to a double-destruction bug?
As an automatic variable, view is destroyed when it goes out of
scope. Then scene goes out of scope and is destroyed. I imagine
that scene is the parent of view in the usual Qt sense, so that
scene's destructor deletes view, which would be a bug.
(I believe that I have seen other code snippets in the Qt documentation
that have this same issue.)
Is this just poetic code-snippet license? Are scene and view not in
a conventional Qt parent-child relationship?
The documentation shows the constructor as:
QGraphicsView ( QWidget * parent = 0 )
Of course, you can call arguments anything you want, but the name
"parent" is suggestive.
Or is the code okay, and there is something I'm missing about
the whole Qt parent-child-ownership-destruction mechanism?
(By the way, I'm looking at QGraphicsScene / QGraphicsView in
follow-up to some suggestions on the list to use them for Qt 2-d
game programming.)
Thanks.
K. Frank
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