[PyQt] Smartpointer to Python

[Phil Thompson]

On Monday 26 May 2008 9:34:00 pm Arve Knudsen wrote:
> 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).

Stroustrup talks of objects being "destroyed by delete". As far as SIP is 
concerned they are synonymous.

Phil