winapi - How to use C++ standard smart pointers with Windows HANDLEs?

Question

I was wondering if there is a way to use unique_ptr<T> with Windows HANDLEs?

I was thinking to replace the std::default_delete with specific handle_trats that calls CloseHandle. The problem is that HANDLE is defined as void* unique_ptr<void> won't compile as sizeof(void) is not defined.

So far I see only two possibilities:

1. Create a wrapper class for HANDLEs and use it like this: unique_ptr<new CHandle(h)>. This pretty much makes the unique_ptr<T> itself useless.
2. Use HANDLE specific smart pointer class that resembles unique_ptr<T>.

What do you think is better choice? What would you suggest?

The question can be extended for COM IUnknown pointers - can CComPtr be replaced by any of the standard smart pointers?

Answer 1

The question can be extended for COM IUnknown pointers - can CComPtr be replaced by any of the standard smart pointers?

Yes. You don't specialize std::default_deleter, you simply replace the deleter type.

struct COMDeleter {
    template<typename T> void operator()(T* ptr) {
        ptr->Release();
    }
};
unique_ptr<IUnknown, COMDeleter> ptr; // Works fine

The same principle applies to shared_ptr and indeed, to HANDLE.