glad to see such a question and I'm happy to share my point. I think you are asking about a bug-fix on the designation of the C++ language itself, not just another C++ language feature. The "bug" has been there for tens of year. That is, the copy constructor.
Copy constructors seems very strange if you know in physics there are lots of things that can not be copied like energy and mass. That's just a joke, but in fact in the world of programming too, objects like exclusive file descriptors are not copyable. So C++ programmers and designers invented some tricks to deal with that. There are 3 famous: NRVO, boost::noncopyable and std::auto_ptr.
NRVO (Named Return Value Optimization) is a technic that lets a function returns an object by value without calling the copy constructor. But the problem with NRVO is that though the copy constructor is not actually called, a public copy constructor declaration is still needed, which means, objects of boost::noncopyable is not compatible with NRVO.
std::auto_ptr is another trial to bypass the copy constructor. You might have seen its "copy constructor" implemented like
template
auto_ptr(auto_ptr<_T>& source)
{
_ptr = source._ptr; // where _ptr is the pointer to the contained object
source._ptr = NULL;
}
This is not a copy at all, but a "move". You could consider this kind of behavior as the prototype of a move semantic.
But std::auto_ptr also has its own problem: it is not compatible with STL containers. So, unfortunately, anything about noncopyable is painful.
That was painful until, the C++0x move semantic is finally published and implemented by the compiler makers.
In simple way, you could just think of move semantic as something same as the "copy" behavior of std::auto_ptr, but with a full support by the language features so it works fine with containers and algorithm.
By the way in C++0x the std::auto_ptr is deprecated and a new template type std::unique_ptr is recommended.
My story will end now. Please refer to other posts if you want to know more about it like strange syntax and rvalue system.
