What about RVO and NRVO?

You still can bind a temporary to a const reference. This is a simple example on how it is possible to do optimizations. Or am I mistaken?

Example:

std::string foo();


void bar()
{
   std::string const& bound_temporary = foo();

   std::cout << bound_temporary;
}

whereas this is invalid:

void invalid_bar()
{
   std::string& bound_temporary = foo(); //will not work, but AFAIK some compilers support it
}

So compilers can do optimizations based on constness.

Regards,
Ovanes

On Fri, Mar 20, 2009 at 12:15 AM, Emil Dotchevski <emildotchevski@gmail.com> wrote:
On Thu, Mar 19, 2009 at 3:49 PM, Ovanes Markarian
<om_boost@keywallet.com> wrote:
> For boost::shared_ptr it's the same. Nothing is copied in both cases. Some
> compilers might (which is under doubt) optimize it better. Since const is an
> additional information for them, that the object is not going to change
> within the called function.

Const in a reference is merely part of the type safety system.
Compilers can not do optimizations based on the constness of a
reference, all they can do is report errors.

Emil Dotchevski
Reverge Studios, Inc.
http://www.revergestudios.com/reblog/index.php?n=ReCode