[C++-sig] set python attribute from C++

Hans Meine meine at informatik.uni-hamburg.de
Thu Jul 17 10:43:13 CEST 2008

On Donnerstag 17 Juli 2008, Gennadiy Rozental wrote:
> > > So the usage scenario is something like this:
> > >
> > > // this may create objects based on pure C++ classes
> > > // or classes implemented in python.
> > > boost::intrusive_ptr<Base> obj = Factory::create(....);
> >
> > This can't work for "classes implemented in Python."  The intrusive_ptr
> > will not be able to maintain Python's reference count.
> This is really out of my hands. All our objects are memory managed through
> these intrusive_ptr like smart pointer. I guess what I need is to prevent
> Boost.Python from managing the C++ objects and manually sync lifetime of
> C++ anf python object.

AFAIK, this is what SIP does, since Qt also manages the lifetime itself.  
However, that means that you have to check in every operation whether the 
underlying C++ object has been deleted (and throw a corresponding Python 
exception).  Alternatively, you risk crashes and call that usage errors.  
(Depending on the actual object lifetimes, this may be practically feasible.)

Ciao, /  /                                                    .o.
     /--/                                                     ..o
    /  / ANS                                                  ooo
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