Re: [boost] shared_ptr deleter introspection?

From: Peter Dimov (pdimov_at_[hidden])
Date: 2002-11-17 08:28:15

From: "David Abrahams" <dave_at_[hidden]>
> In Boost.Python, I am going to start using custom deleters to enable
> me to produce shared_ptr<T> from any Python object which contains a T,
> while keeping the Python object alive. I can't believe I didn't think
> of this earlier, and I want to thank Peter Dimov for putting me onto
> the idea.
>
> Each such shared_ptr<T> contains a pointer to the owning Python
> object, whose identity is associated with that of the T object it
> contains. When these shared_ptrs are converted back to Python, I
> currently have to build a new Python object around a copy of the
> shared_ptr<T>, so that now there are two Python objects using the same
> C++ object's "guts". It would be very useful if I could introspect
> about the deleter, and find out that it was using my custom deleter,
> extract the Python object pointer, and simply return that instead of
> building a new Python object.
>
> Looking at the code, I can see a few ways to hack that functionality
> in, but I wonder if we should think about making it part of the public
> interface? After all, the deleter is part of the public interface for
> shared_ptr creation...

shared_ptr introspection is something that I've been considering lately. In
particular:

void const * shared_ptr::get_original_pointer() const;
std::type_info const & shared_ptr::get_element_type_info() const;

I haven't encountered a need to inspect the deleter yet... what interface
are you suggesting?