[C++-sig] Can boost.python and PyQt be used together?

[David Abrahams]

"Paul F. Kunz" <Paul_Kunz at SLAC.Stanford.EDU> writes:

>>>>>> On Sun, 08 Dec 2002 18:04:37 -0500, David Abrahams <dave at boost-consulting.com> said:
>
>> Err, Paul: when I suggested that you use return_internal_reference<>
>> for your newCanvas call, I didn't mean that you should blindly
>> substitute it for reference_existing_object everywhere!
>
>    Sorry.
>
>> You probably shouldn't be using call policies until you understand
>> what these things do. What is unclear when you RTFM? I mean, in
>> particular, the 3 sections starting here:
>> http://www.boost.org/libs/python/doc/v2/reference.html#models_of_call_policies
>
>    Upon reading them again, I'm not sure.   But...
>
> - the example for `return_internal_reference' looked like my case, but
>   now I realize it is for a member function not a global function.
>   My mistake.

Did you read
http://www.boost.org/libs/python/doc/v2/return_internal_reference.html#introduction
or did you just look at the example usage?

>
> - The example for `reference_existing_object' seems to be in error.
>   it is not a template argument for `return_value_policy'.

Yes, that's been fixed in CVS for quite some time:

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/boost/boost/libs/python/doc/v2/reference_existing_object.html#examples


> Ok, so now I have...
>
>   def ( "WCFactory", WCFactory, 
>    	return_value_policy < reference_existing_object > () );
>
>   class_ <WindowController> ( "WindowController" )
>     .def ( "newCanvas", 
> 	   ( CanvasWindow * ( WindowController::* ) // function pointer
> 	     (void) ) // arguments
> 	   &WindowController::newCanvas,
>  	   return_internal_reference <> () )
>     ;
>
> So if I understand it, the *this, ie the WindowController object owns
> the returned CanvasWindow, which is what I want.

Actually, the returned CanvasWindow Python object owns the
WindowController, which is what you want ;-)

It's a little counterintuitive, but that's correct.

>    I think the problem is not in Boost.Python incompatiblity, but in
> my code.   I think my Window is trying to do something before the Qt
> application object is running.   I'll have write some more code to
> test that.
>
>    Thanks again for all your help, David and Phil.

My pleasure.

-- 
                       David Abrahams
   dave at boost-consulting.com * http://www.boost-consulting.com
Boost support, enhancements, training, and commercial distribution