On 14 January 2014 18:36, Jakob Ovrum <jakobovrum@gmail.com> wrote:

On Tuesday, 14 January 2014 at 08:23:05 UTC, Manu wrote:

1. A termination condition (ie, while)

foreach(t; things) iterates each thing, but it's common in traditional for
loops to have an && in the second 'while' term, to add an additional
termination condition.
for(i=0; i<things.length && things[i].someCondition; ++i)

Or with foreach:
foreach(i, t; things)
{
  if(t.someCondition)
    break;
  ...
}

foreach(t; things.until!(t => t.someCondition))
{
}

Unfortunately foreach over a range does not automatically support an index loop variable. We could add something like std.range.enumerate to support this, but I think it's a common enough requirement that a language amendment is warranted (there are some subtleties involved in implementing it though - specifically when combined with automatic tuple expansion).

2. A filter

The other thing is the ability to skip uninteresting elements. This is
typically performed with the first line of the loop testing a condition,
and then continue:
foreach(i, t; things)
{
  if(!t.isInteresting)
    continue;
  ...
}

foreach(t; things.filter!(t => t.isInteresting))
{
}

Ditto about the index loop variable.

I've tried to approach the problem with std.algorithm, but I find the
std.algorithm statement to be much more noisy and usually longer when the
loops are sufficiently simple (as they usually are in my case, which is why
the trivial conditions are so distracting by contrast).

The two examples above look a *lot* cleaner and less noisy (declarative!) to me than the imperative approach using if-break or if-continue.

/agree completely.

This is nice, I didn't think of writing statements like that :)

That's precisely the sort of suggestion I was hoping for. I'll continue like this.