Re: [boost] out_ptr review is extended until Wednesday, July 10

On Wed, Jun 26, 2019 at 11:05 PM Gavin Lambert via Boost < boost@lists.boost.org> wrote:

On 27/06/2019 13:52, Bagaskoro Kang wrote:

...

the creator apis have two out params: Interface** pointer and unsigned* size and the destroyer functions must be called with pointer and the size.

Interface** obj; unsigned size; int ret = Create(... ... ... &obj, &size);

and then we need to call a Release(obj, size) if the ret is success.

I do not think I can use the out_ptr with these APIs ???

struct sized_deleter { unsigned size; ... }; using bop = boost::out_ptr; std::unique_ptr p_obj; int ret = Create(..., bop::out_ptr(p_obj), &p_obj.get_deleter().size) if (LIBNAME_HAS_FAILED(ret)) { throw std::runtime_error("deep sadness"); } This example is less pretty because I'm putting the size in the deleter, but it works.

...

also we call the Linux kernel C API posix_memalign() and we assign to unique_ptr. is not possible to use out_ptr with ?

std::unique_ptr upNumf; void * pNumf; int ret = posix_memalign(&pNumf, 64, nNumf); if (!ret) upNumf.reset((Numf*)pNumf);

using bop = boost::out_ptr; std::unique_ptr upNumf; int ret = posix_memalign(bop::out_ptr(upNumf), 64, nNumf); if (ret != 0) { throw std::runtime_error("something went wrong, but at least we're not leaking memory here."); } Casting support is built in to the API: you can go from strongly typed pointers to void**, or other related pointers by passing the type as a template argument.