C++14: Shared Lock Type

C++14 added a Shared Lock Type. Here is an example:

#include <iostream>
#include <mutex>
#include <shared_mutex>

int main()
{
  std::shared_timed_mutex MySharedTimedMutex;

  std::shared_lock<std::shared_timed_mutex>
                                    MySharedLock(MySharedTimedMutex);
  if (MySharedLock.owns_lock())
  {
    std::cout << "R+ ";
  }
  else
  {
    std::cout << "R- ";
  }

  std::shared_lock<std::shared_timed_mutex>
                                   MySharedLock2(MySharedTimedMutex);

  if (MySharedLock2.owns_lock())
  {
    std::cout << "R+ ";
  }
  else
  {
    std::cout << "R- ";
  }

  MySharedLock.unlock();
  MySharedLock2.unlock();

  std::unique_lock<std::shared_timed_mutex>
                                    MyUniqueLock(MySharedTimedMutex);
  if (MyUniqueLock.owns_lock())
  {
    std::cout << "W+ ";
  }
  else
  {
    std::cout << "W- ";
  }
  return 0;
}
// Output: R+ R+ W+

Reference: http://en.cppreference.com/w/cpp/thread/shared_lock/shared_lock