[PyKDE] Issue with QDialog and lifetime

Phil Thompson phil at riverbankcomputing.co.uk
Thu Jul 7 15:01:36 BST 2005

> Phil Thompson <phil at riverbankcomputing.co.uk> wrote:
>> 1. Either add an optional parameter to exec_loop() which does the
>> transfer
>> or have exec_loop_and_transfer() (or something less of a mouthful). At
>> least that way it won't break existing code.
> I like this solution. Then I can do:
> class QDialog(QDialog):
>     exec_loop = QDialog.exec_loop_and_transfer
> sys.modules["qt"].__dict__("QDialog") = QDialog

I don't really like it. I've realised that my worry about seg faults is
misplaced - it's an issue for generic SIP generated bindings, but Qt's
parent/child handling will avoid it in this case - so I'm reconsidering
the original proposal.

The original proposal would cause problems in the following scenario...

1. One or more modal dialogs that are hidden when not used, rather than
being re-created each time they are needed.

2. The dialogs are Python sub-classes of QDialog or the dialog has
instance objects (ie. there are useful Python objects tied to the C++

3. No application references to the dialogs are maintained. The
application relies on finding a dialog again by searching its parent's

This would seem to be an untypical way of doing things - is anybody going
to shout that their 5 million line application relies on this technique?

In fact, from a consistency point of view, I think I might prefer to make
the solution apply to all dialogs - by removing the /TransferThis/ from
the ctors.


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