[C++-sig] Re: call_method

[Brett Calcott]

>
> I'm thinking we should do this:
>
> 1. Set up Boost.Python so that shared_ptr<T> can be extracted from any
> Python object from which we can extract T*... no matter how it's
> held! You can do this by using a custom deleter that holds the Python
> object and keeps it alive. See the section titled:
>
>    "Using a shared_ptr to Hold Another Shared Ownership Smart Pointer"
>
> I find this very exciting, and can't believe I didn't think of it
> earlier!!
>
> 2. Prepare a special "self_base" class that can be used as a base of
>    "callback" classes like BaseWrap from the examples. This base would
>    hold the "self" pointer. It would also provide a family of
>    convenience functions which implement call_method<> on the held
>    self pointer without having to explicitly mention it (hmm, I'm not
>    sure I can make this work out on msvc6. But that's another
>    issue). Most-importantly, when references and (smart) pointers to
>    polymorphic classes are converted to python, we will attempt to
>    downcast to "self_base", and if successful, we'll return the
>    contained self pointer instead of a new object.
>

Ok, I understand 2. This gets around having to create to_python converters.
But I don't yet see how 1. can work. Is the 'other shared pointer' the
Python reference count? Or the shared_ptr declared in class_<...>? Can you
elucidate?


Cheers,
Brett