on Wed Aug 12 2009, Ion Gaztañaga <igaztanaga-AT-gmail.com> wrote:
David Abrahams escribió:
Very great news to hear that this project is moving forward (so to speak ;-))
Let's hope this is the final step!
The library has now new macros to declare copyable and movable types and movable only types. Old macros are still there for backwards compatibility (specially unordered library which was also ported to this move sandbox) but I expect to remove them if current approach is considered better.
->Updated documentation and tests.
http://svn.boost.org/svn/boost/sandbox/move/libs/move/doc/html/move/composit...
still says "all moves occur explicitly," but I think you mean "all moves from lvalues," right?
Yes. The new library now moves non-const rvalues in assignments:
copyable_and_movable produce();
copyable_and_movable cm; for(;;){ //now moved instead of copied! cm = produce(); }
Only in assignments? what about consume(produce()) scenarios?
This is not the case with constructors (the original Klaus Triendl proposal included them, http://lists.boost.org/Archives/boost/2009/06/153266.php) because it terribly uglifies syntax
Are you sure you've looked at all the alternatives? Every move library I'm aware of before yours supports implicitly move constructing from non-const rvalues.
(there is no way in C++03 to automatically generate constructor overloads that forward to another constructor) and because that case is in practice more efficient than moving thanks to RVO:
for(;;){ //Copied? No, RVO avoids copy copyable_and_movable cm = produce(); }
You might check whether direct initialization is just as efficient as copy initialization before you say that: copyable_and_movable cm((produce())); IIRC EDG-based compilers used to only elide copies in the copy initialization case (!) -- Dave Abrahams BoostPro Computing http://www.boostpro.com