[PyQt] Smartpointer to Python
arve.knudsen at gmail.com
Mon May 26 21:34:00 BST 2008
On 5/26/08, Phil Thompson <phil at riverbankcomputing.com> wrote:
> On Monday 26 May 2008 2:10:53 pm Arve Knudsen wrote:
> > On Mon, May 26, 2008 at 2:37 PM, Phil Thompson
> > <phil at riverbankcomputing.com> wrote:
> > > On Monday 26 May 2008 1:10:11 pm Arve Knudsen wrote:
> > >> Hi
> > >>
> > >> Reading the SIP documentation I can't find any info on how C++ objects
> > >> are deleted (returned to the heap) from Python, only that their
> > >> destructor is called.
> > >
> > > ...when the Python object is garbage collected and if the C++ object is
> > > owned by Python.
> > Yes, that much is clear.
> > >> Does this mean that when returning new'ed
> > >> pointers to Python they should be managed by smartpointers? If so, is
> > >> there any mechanism in SIP for treating smartpointers as objects of
> > >> their managed type from Python?
> > >
> > > SIP effectively implements its own smartpointer mechanism - so long as
> > > the C++ type has a virtual dtor and the C++ object is created from
> > > Python.
> > Could the SIP documentation be more clear about this? I can only see
> > that it says that pointers to C structs will be free'ed, and that C++
> > objects are destroyed. I need to make sure that C++ objects are
> > deleted, not just destroyed.
> ...err, what's the difference?
Can you define "destroying" a C++ object as deleting it? When you say
destroy, I think of invoking its destructor. A destroyed object isn't
necessarily freed, and it's not immediately obvious how to free a
heap-allocated object in C++ (depends on how it's allocated).
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