On Wed, 07 Sep 2011 20:50:04 +0200, Johannes Totz <johan...@jo-t.de> wrote:
On 06/09/2011 12:00, bearophile wrote:
malio:
Okay, thanks bearophile. But I currently doesn't exactly understand
what's the difference between "ref" and "const ref"/"immutable
ref". If "ref" is syntactic sugar for pointers only (like your
first example), does it also create a copy of the parameters which
are marked as "ref"? I thought that pointers (and in this context
also "ref") avoid the creation of costly copies?!?
"ref" just passes a reference to something, so it doesn't perform
copies.
"const ref" or "immutable ref" just means that you can't change the
value (with the usual semantic differences between const and
immutable, that are both transitive).
So if a parameter is immutable (without ref) the compiler could infer a
ref to avoid copy because it can't be modified?
Theoretically at least. I don't believe such an optimization is actually
performed in current D compilers.
--
Simen
