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?
3. The only controversial part I see is that `break` doesn't break from
the foreach loop. While I agree with the reasoning, and support that
concept, the truth is we currently have a "poor man's" static foreach
using a foreach over a tuple, and that DOES break from the loop.
For instance:
size_t idx;
switch(someval)
{
case something:
foreach(v; AliasSeq!(1, 2, 3))
{
if(shouldBreak(v))
break; // today, this jumps to moreProcessing() line
}
moreProcessing();
break;
}
If I replaced foreach with static foreach(v; 1 .. 4), it now breaks out
of the switch?
As much as I would rather see the proposed behavior, I feel it's too
confusing given the existing foreach behavior. I think in this case, you
have to require a break label.
A possible deprecation path:
1. In the case where "static foreach" is inside another construct that
allows breaking, require a break label. However, foreach over a tuple
would continue to exhibit today's behavior.
2. print warning message for foreach over a tuple that contains a break
without a label. Warn users that a future version will not allow
breaking from the foreach.
3. disallow breaking out of the foreach directly (i.e. jumping to the
closing brace of the loop), even if there is a label (you can surround
foreach with a do{} while(false) if you need this behavior).
4. Remove the requirement for labeling. Both static foreach and foreach
on a tuple do not break from the loop construct.
-Steve
