[Development] parented_ptr

[Marco Bubke]

On 10/16/25 13:01, Schimkowitsch Robert wrote:
> What about a smart pointer that
> - Tracks it's QObject using QPointer internally
> - In it's destructor, checks if the object still exists
> - If so, checks if the object has a parent
> --> It has a parent: Don't delete
> --> It has no parent: Delete
> 

You mean something like:


namespace Internal {

template<typename Type>
struct UniqueObjectPtrDeleter
{
     using pointer = QPointer<Type>;

     constexpr UniqueObjectPtrDeleter() noexcept = default;
     template<typename UpType, typename = 
std::enable_if_t<std::is_convertible_v<UpType *, Type *>>>
     constexpr UniqueObjectPtrDeleter(const 
UniqueObjectPtrDeleter<UpType> &) noexcept
     {}

     constexpr void operator()(pointer p) const
     {
         static_assert(!std::is_void_v<Type>, "can't delete pointer to 
incomplete type");
         static_assert(sizeof(Type) > 0, "can't delete pointer to 
incomplete type");

         if (not p.parent())
             delete p.data();
     }
};

} // namespace Internal

template<typename Type>
using UniqueObjectPtr = std::unique_ptr<Type, 
Internal::UniqueObjectPtrDeleter<Type>>;

template<typename Type, typename... Arguments>
auto makeUniqueObjectPtr(Arguments &&...arguments)
{
     return UniqueObjectPtr<Type>{new 
Type(std::forward<Arguments>(arguments)...)};
}


I think you can simply write your own deleter for std::unique_ptr.