Re: [pygccxml-development] Parameter passing, ownership semantics

[Roman Y. <rom...@gm...>]

On 2/18/07, Gustavo Carneiro <gjc...@gm...> wrote:
>   Take this program, where Simulator and EventImpl are C++ classes wrapped
> by Py++ / boost python:
>
> class MyEvent(EventImpl):
>
>     def Notify(self, *args):
>          print "Notify!", args
>
>
>  ev = MyEvent()
> t1 = Seconds(1)
>  Simulator.Schedule(t1, ev)
> Simulator.Run()
>
>   There's a memory error here because 'ev' is passed into Simulator, which
> takes ownership of the value and eventually calls delete on C++ counterpart
> to 'ev'.  valgrind says that Address 0xsomething is 8 bytes inside the
> object allocated by boost python.
>
>   If, OTOH, I do "Simulator.Schedule(Seconds(1), MyEvent())", then the
> python objects are prematurely destroyed, and another memory error occurs .
>
>   I notice that Py++ "call policies" are always related to the return value;
> I don't see how to customize the parameter passing aspect of it all.
>
>   Any advice is appreciated.  Thanks in advance.

I don't fully understand your situation. Take a look on this FAQ(
http://boost.org/libs/python/doc/v2/faq.html#ownership )

Does it help?

If not, please describe your situation with some C++ code.

If it do help, than you can use "function transformation" feature to
create the wrapper.

( http://language-binding.net/pyplusplus/documentation/functions/transformation/built_in/built_in.html
)


Thanks.

-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/