On Monday, 22 April 2013 at 20:02:12 UTC, Andrei Alexandrescu
wrote:
In a way I wish my not being polite would be the main
bottleneck for this. I've been extremely busy at work, then
preparing for DConf 2013, and last week has been quite
distracting what with the Boston bombings three miles away from
where we live and all that. It strikes me as odd to be
obligated to spend time on something just because someone else
did, and framed as impolite if I don't.
Thanks for your time. Sometimes even simple "Have seen it, will
answer later / after DConf is priceless".
That being said, I have made a pass through this DIP and I have
the following concerns about it.
1. It defines a new language feature instead of improving the
existing ones. At this point in the development of the
language, our preference should be putting the existing
features in good order.
You consider "scope" a new language feature? And consider "auto
ref" improvable solution. The very point of this DIP is to not
create syntax-driven features, instead better define existing
ones that make sense on their own so they can be used for same
purpose.
2. The proposal is sketchy and does not give many details, such
as the lifetime of temporaries bound to scope ref objects.
It can't because lifetime of temporaries is not defined in D at
all and suck stuff needs to be consistent. It is not really
different from a lifetime of struct literal temporary used for
pass-by-value.
3. The relationship with auto ref is insufficiently described,
e.g. there should be clarification on why auto ref cannot be
improved to fulfill the desired role.
auto ref is a template-world entity. If by "improved" you mean
"completely reworked" than sure, I can add this rationale. Will
do today.
4. Above all this is a new language feature and again we want
to resort to adding new feature only if it is clear that the
existing features are insufficient and cannot be made
sufficient. In particular we are much more inclined to impart
real, demonstrable safety to "ref" and to make "auto ref" work
as a reference that can bind to rvalues as well as lvalues.
Can't agree. "scope" is defined (but not implemented, a pity).
Creating temporaries already exists for some cases. No really new
language feature is added. No special syntax created. "scope ref"
is still "scope" and "ref" with all semantics this imposes,
rvalue references are just a side-effect. Contrary to this, "auto
ref" IS a new feature created specifically for syntax hack. That
is a very problem you are speaking about - introducing new
concepts instead of making use of ones that exist for ages.
