unique_ptr usage

unique ptr in cpp

std::unique_ptr is used to replace auto_ptr.

When you say std::unique_ptr<T>, the unique_ptr constructor expects to receive a T*, but CreateMutex returns a HANDLE, not a HANDLE *.

we can use std::remove_pointer to get to the HANDLE‘s underlying type.

When use it in windows API and deal with HANDLE, we need a different method to construct it using lambda delter and decltype to deduce the type of the function pointer.

std::unique_ptr<std::remove_pointer<HANDLE>::type, 
                decltype(&::CloseHandle)> m_mutex(::CreateMutex(NULL, FALSE, NULL),
                                                  &::CloseHandle);