Dmitry Olshansky:
An expression attribute? Why turn language into a mess over
this tiny problem?
It seems to me that you are considering solutions that add
arbitrary amounts of complexity to solve relatively small
problems.
...
That "just" epithet is remarkable self-destruction.
Please be more gentle toward others. Your attitude is poisonous
for creativity, and while I have a thick hide and I can ignore
comments like this, similar answers could scare away other people
from contributing to the discussions. The lack of tact and basic
human kindness is a common problem in technical forum. I
sometimes do the same mistake, but we should try to be better.
Your good work on the regex module shows you are intelligent and
qualified, so I'm sure you can also be better toward others.
Regarding the technical topic, array bound checks are not a tiny
problem, and it's not a huge one. D has switches and logic to
enable and disable them. The Oracle JavaVM ha a good amount of
logic to optimize away array bound checks. Similar logic is
visible in other language compilers. Ada language has refined
features that allow the compiler to safely remove some bound
checks without too much inference work. There are several papers
on this topic, like the one I've shown in the first post, that
show that several intelligent people have studied this topic
extensively. Experimental high-performance numeric languages like
X10 and Chapel contain several strategies to avoid array bound
checks safely. The experience with both famous bugs and the daily
experience in debugging programs shows that out-of-bound array
access is a frequent source of some of the worst bugs. There are
papers that show a 20-100% improvement in performance coming from
disabling array bound checks in programs that use arrays a lot,
like most scientific programs. And D language seems fit for some
heavy numerical work. D Zen considers quite important both
performance and safety, so adding logic to the compiler to remove
some more array bounds is a very good way to do both things at
once.
Regarding my idea of the @bounded, perhaps it's stupid and
useless, but you have to understand that it's just an idea. Most
ideas are not even wrong, but sometimes the wrong ones lead to
better ideas, that sometimes are useful. This has happened many
times even in the D history (like my refused suggestion for the
@noheap attribute. Now we have @nogc and I like it a lot, it
allows me to understand better what my code is doing). If you
criticize too much the people that invent ideas, you will have no
future.
Bye,
bearophile
