On 7/12/17 4:23 AM, Timon Gehr wrote:
On 12.07.2017 01:18, Steven Schveighoffer wrote:
On 7/10/17 4:53 AM, Mike Parker wrote:
As promised, since there has been zero feedback on DIP 1010, "Static
foreach", in either the Draft or Preliminary review rounds, I'm going
to skip the normal two-week feedback cycle on the Formal review. If
there are no major criticisms or objections raised in this thread,
then sometime on Thursday of this week I'll send Walter & Andrei an
email kicking off the decision process.
So, if you have any thoughts on the DIP, now is the time to express
them.
Thanks!
https://github.com/dlang/DIPs/blob/master/DIPs/DIP1010.md
A few things:
1. I can't wait for this to get in. I'm anticipating success :)
2. I see no point in having foreach(enum i; 0.. 3) when static
foreach(i; 0 .. 3) works just fine?
...
foreach(enum i; 0..3) does not currently compile and is not proposed in
this DIP, but it would be useful for the case where you need an unrolled
foreach loop.
It's in the DIP, regardless of whether it's critical to the acceptance
of the DIP. As it's something on the table for W&A to look at, I wanted
to voice my opinion on it.
I don't see why for foreach, break behaviour should depend on the
aggregate, that is much more confusing.
Perhaps. My point of view is that I'm generally using foreach over a
tuple to generate switch cases. I always think that the break is going
to apply to the switch statement, and it gets me every time. In fact, in
writing this post, I just found a (harmless?) bug in my code:
switch(str)
{
foreach(n; names)
{
case n:
...
break;
}
default:
break;
}
It's harmless because the default case does nothing. But it certainly
isn't what I should have written!
I think of foreach over a tuple as separate from foreach over a runtime
type. To me, it's already a different syntax and more akin to static
foreach. One may argue that static foreach looks just like foreach, and
so all of them should behave the same.
static foreach is not a loop
with a loop body, it generates multiple versions of the given code.
There is no reason why static foreach and foreach should have "the same"
(whatever that even means!) behaviour with respect to runtime break, and
if it is really considered too confusing, static foreach should just
always require an explicit label. (But this is painful for me to
implement, as it is unnatural.)
From a user perspective, whether I reach for one tool or the other, the
behavior shouldn't be subtly different. If I'm looking for a tool to
unroll loops, I can use foreach with a tuple, or static foreach. Both
should behave the same.
Perhaps the deprecation path should include a removal of straight
foreach over a tuple working (use static foreach explicitly). This would
make the distinction even more obvious.
-Steve
