[PyQt] Parent child relationship: child survives parent

[Phil Thompson]

On Fri, 12 Jul 2013 09:30:46 +0200, Volker Pilipp
<volker.pilipp at dectris.com> wrote:
> I've got a little bit confused about ownership of objects in SIP  As
> far as I understand, if ParentObject owns ChildObject, the destruction
> of ChildObject is left to c++ i.e. the c++ destructor of ParentObject
> is expected to destruct ChildObject.  This behaviour may result in a
> seg fault if the python programmer does not make sure that ChildObject
> goes out of scope before ParentObject does. Indeed, there are many
> scenarios where this may happen accidentally.

If you are talking about QObject then you shouldn't get a segfault - you
should get a Python exception.

> That's what I would like to have:  The ChildObject keeps a reference
> on ParentObject that is released during destruction of ChildObject,
> where the Python destructor of ChildObject must  not  call the c++
> destructor of the wrapped c++ instance (this is done during
> destruction of ParentObject).

The Python destructor will not call the C++ destructor if the C++ instance
has a parent. If you think it does then provide a test case that
demonstrates it.

> I am wondering if this behavior is possible to achieve in SIP.

Phil