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.
