On Friday, 10 April 2015 at 23:12:55 UTC, deadalnix wrote:
On Friday, 10 April 2015 at 10:02:01 UTC, Martin Nowak wrote:
On Wednesday, 8 April 2015 at 23:11:08 UTC, Walter Bright
wrote:
http://wiki.dlang.org/DIP77
So someone passes an RCO via ref to avoid the inc/dec, and
because that imposes safety issues we turn it into some sort
of pass by value under the hood, defeating the purpose, and
provide an opt-out via @system opAssign.
Wouldn't it more straightforward to make pass-by-ref unsafe
(@system) for RCOs?
Then the only thing missing to make this equally powerful,
would be an optimization opportunity for the compiler to elide
copies of pass-by-value RCOs, e.g. it could avoid calling the
postblit when the function retains the refcount.
Only the first pass by ref create a copy. You can then pass the
ref down all you want without copy.
That is an acceptable cost IMO.
It's not acceptable that it happens behind the user's back.
Costly operations must be explicit.
