[Development] Deleter that calls deleteLater() for use with std::unique_ptr<> and other smart pointers

[Nikita Krupenko]

On среда, 19 апреля 2017 г. 20:58:28 EEST Ville Voutilainen wrote:
> On 19 April 2017 at 20:48, Konstantin Tokarev <annulen at yandex.ru> wrote:
> > 19.04.2017, 20:43, "Thiago Macieira" <thiago.macieira at intel.com>:
> >> On quarta-feira, 19 de abril de 2017 06:44:24 PDT Konstantin Tokarev 
wrote:
> >>>  Hello,
> >>>  
> >>>  I think it will be a good idea to provide implementation of functor
> >>>  calling
> >>>  deleteLater() instead of delete which can be used with std::unique_ptr,
> >>>  std::shared_ptr and other smart pointers with compatible interface.
> >>>  
> >>>  We already have QScopedPointerObjectDeleteLater, however it implements
> >>>  cleanup(T*) instead of operator()(T*).
> >>>  
> >>>  Any suggestions how to name this new class and where to place it?
> >> 
> >> QSharedPointer already supports a PMF as a deleter.
> >> 
> >>         auto ptr = QSharedPointer<QObject *>(new QObject,
> >>         &QObject::deleteLater);
> >> 
> >> So I think this actually belongs in the std-proposals mailing list, not
> >> in Qt.
> >> 
> >> Until C++20 gets it, you can use a lambda.
> > 
> > It's not possible to have members with auto-deduced types in non-template
> > class, so I actually cannot.
> 
> I fail to see what auto-deduced members have to do with it:
> 
> std::unique_ptr<QObject, void(*)(QObject*)> upqobj{nullptr,
> [](QObject* obj) { obj->deleteLater(); }};

BTW, is there any advantage of using lambda over the following construction?

std::unique_ptr<QObject, decltype(std::mem_fn(&QObject::deleteLater))>
(ptr, std::mem_fn(&QObject::deleteLater));