[PyQt] How to write handwritten code to access the C++ object when the corresponding python object destroyed?

[Weitian Leung]

One more question, is it possible to insert handwritten code to the
MappeedType's release_XXX?

When mapped one type to python's str, which type has it's own alloc method
(The BSTR for example, SysStringAlloc etc). After passed to the C++ call
and returned, we need to free the memory using it's own dealloc method.

So is it possible do that? Or other way to call the dealloc method...

On Wednesday, February 19, 2020, Weitian Leung <weitianleung at gmail.com>
wrote:
> Thanks, it works!
>
> On Wednesday, February 19, 2020, Phil Thompson <
phil at riverbankcomputing.com> wrote:
>> On 17/02/2020 14:35, Weitian Leung wrote:
>>>
>>> Hi,
>>>     I'm noob in SIP. Say I have two abstract interfaces and one method
to
>>> create the object:
>>>
>>> struct IUnknown /Abstract/
>>>>
>>>> {
>>>>     virtual void AddRef() = 0;
>>>>     virtual void Release() = 0;
>>>>
>>>>     %GCClearCode
>>>>         printf("GCClearCode\n");
>>>>     %End
>>>> };
>>>>
>>>> struct IDemo : public IUnknown /Abstract/
>>>> {
>>>>     virtual void SayHi() = 0;
>>>> };
>>>>
>>>
>>> void createDemo(IDemo **demo /Out/);
>>>>
>>>
>>>
>>> Using in python side:
>>> idemo = demo.createDemo()
>>> idemo = None
>>>
>>> Is it possible to write some handwritten code that call the Release
method
>>> when idemo set to None or when  idemo doing GC?
>>> Or if we can call AddRef automatically when idemo assign to another
object.
>>>
>>> I known that on python side we can call AddRef/Release to make it works,
>>> but I want the code more python's way.
>>>
>>> The %GCClearCode handwritten code never called in this case.
>>> And the %GCTraverseCode handwritten code only call when the object make
an
>>> assignment to other object.
>>> Am I missing something?
>>>
>>> Please check the full code in the  attached file.
>>
>>
https://www.riverbankcomputing.com/static/Docs/sip/c_api.html#event-handlers
>>
>> I've only just realised that that documentation is incomplete. The two
event types currently implemented are...
>>
>> sipEventWrappedInstance,    /* After wrapping a C/C++ instance. */
>> sipEventCollectingWrapper,  /* When garbage collecting a wrapper object.
*/
>>
>> ...and the corresponding event handler signatures are...
>>
>> typedef void (*sipWrappedInstanceEventHandler)(void *sipCpp);
>> typedef void (*sipCollectingWrapperEventHandler)(sipSimpleWrapper
*sipSelf);
>>
>> Phil
>>
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