On Sun, Jun 10, 2012 at 3:24 PM, Mathias Gaunard <mathias.gaunard@ens-lyon.org> wrote:
On 09/06/2012 22:49, Giovanni Piero Deretta wrote:
As per http://cpp-next.com/archive/2009/08/want-speed-pass-by-value/ , if the function is likely to consume or copy the parameter, the best solution is to pass by value. This means you'll only need to provide a single overload.
That is not true. This technique only applies if you need to make a copy at an arbitrary place, not in a particular subobject.
Apart from the fact that "an arbitrary place" in your sentence would seem to cover anything, to what subobject are you referring to? The only thing I can think of is assignment operators of derived classes that need to forward to base classes. In that case I agree that pass by value does not work very well (I usually still use pass by value, but implement operator= in term of swap, which forwards to the base class swap). -- gpd