On Tue, Oct 4, 2011 at 4:52 PM, Nathan Ridge <zeratul976@hotmail.com> wrote:
I meant in the case where operator+ returns a type&&.
Then the object in question is a local variable inside operator+, which will not live past the point when operator+ returns.
No it's not, it's a reference to a passed in parameter. For instance: Type&& operator +( Type&& left, Type const& right ) { left += right; return std::move( left ); } You only return an r-value reference in the case that at least one of your parameters is an r-value reference. The reference is to that particular argument. Here, the first argument is returned by reference, not a local variable. In this way, not even a move-constructor is called (nor required) and no third object is ever created. Anyway, as was pointed out, this is probably not a good idea for other reasons, such as people expecting to be able to bind the result to a reference and have its life extended (though I suppose you could just rule-out such uses as valid when the base is used). -- -Matt Calabrese