What are the advantages of boost::noncopyable

Question

To prevent copying a class, you can very easily declare a private copy constructor / assignment operators. But you can also inherit boost::noncopyable.

Answer 1

I'd rather use boost::noncopyable than manually delete or privatize the copy constructor and assignment operator.

However, I almost never use either method, because:

If I am making a non-copyable object, there has to be a reason it is non-copyable. This reason, 99% of the time, is because I have members that can't be copied meaningfully. Chances are, such members would also be better suited as private implementation details. So I make most such classes like this:

struct Whatever {
  Whatever();
  ~Whatever();
  private:
  struct Detail;
  std::unique_ptr detail;
};

So now, I have a private implementation struct, and since I've used std::unique_ptr, my top-level class is non-copyable for free. The link errors that come from this are understandable because they talk about how you can't copy a std::unique_ptr. To me, this is all the benefits of boost::noncopyable and a private implementation rolled into one.

The benefit with this pattern is later, if I decide that I did indeed want to make my objects of this class copyable, I can just add and implement a copy constructor and/or assignment operator without changing the class hierarchy.