Rvalue references - The resolution

[deadalnix]

On Saturday, 4 May 2013 at 22:33:58 UTC, Walter Bright wrote:
> To put it another way, we wish to solve the problem without 
> introducing more annotations. Rust's solution requires 
> additional annotations, and so is not what we're looking for.

Require isn't the right word, or you hav to explain yourself much 
more.

For instance, see : 
http://smallcultfollowing.com/babysteps/blog/2012/07/19/yet-another-tutorial-on-borrowed-pointers/

"So far we have always used the notation &T for a borrowed 
pointer. However, sometimes if a function takes many parameters, 
it is useful to be able to group those parameters by lifetime."

In other terms, you need to have several parameters that passes 
by ref + return by ref + you want a different lifetime for your 
returned value than union of parameters's lifetime.

Which is a very specific case. That is far away from require. 
That is most case don't require anything, while 1% require an 
explicit lifetime. Unless you do some goofy stuff, you don't even 
need to know about it. And if we decide that no explicit lifetime 
== runtime check, it is never ever required. Just provided for 
the dev that want to have the runtime check removed.

If we get more actual, return by ref in D are mostly usefull for 
collections and ranges. None of theses would require explicit 
lifetime ever.