[pr-645] Add offset to reset() and end()

Hi Levi,

On Fri, Apr 18, 2014 at 9:17 AM, Levi Morrison morrison.levi@gmail.comwrote:

On Thu, Apr 17, 2014 at 6:39 PM, Tjerk Meesters tjerk.meesters@gmail.comwrote:

Hi,

I've added a PR that satisfies #31375.

https://github.com/php/php-src/pull/645

It adds a second optional argument to reset() and end() to specify the
number of elements that should be skipped (forward or backward).

Currently, negative offsets are ignored. Should we raise a notice for such
cases? Something like:

"Negative offsets are not supported."

Any feedback is welcome. Thanks!

Do you have a specific use-case for these changes?

Surely you must have seen the feature request on bugs.php.net ;-)

One example could be, traverse array but skip the first N elements:

$array = [1, 2, 3];
for (reset($array, 1); $current = each($array); ) {
    var_dump($current['value']);
}
// output: int(2) int(3)

Or, get second last element:

$second_last = end($array, 1); // int(2)

--

Tjerk

On Fri, Apr 18, 2014 at 2:39 AM, Tjerk Meesters <tjerk.meesters@gmail.com

wrote:

Hi,

I've added a PR that satisfies #31375.

https://github.com/php/php-src/pull/645

It adds a second optional argument to reset() and end() to specify the
number of elements that should be skipped (forward or backward).

The last time that I can remember discussion of something like array_seek()
[1]–which is what this seems like it actually wants to be–the reception was
fairly positive, but the idea just fizzled out. I’d recommend looking back
over the archives for other similar discussions.

I would be -1 on changing reset() and end() to make them be able to not
reset the array pointer, or not move to the end, respectively; especially
where a neater (IMO) alternative has already been discussed.

[1] http://markmail.org/thread/sczgritz5jcccnwh [PHP-DEV] array_seek
function

Currently, negative offsets are ignored. Should we raise a notice for
such
cases? Something like:

"Negative offsets are not supported."

Any feedback is welcome. Thanks!

The reset() part seems to already be adequately covered by LimitIterator.
Personally I'd prefer not to add any new functionality to reset/current/...
because you oughtn't be using those functions anyway. Trying to do manual
array iteration with them is both somewhat unsafe (think nested iteration)
and makes for really ugly code.

// skip 10 elements of $it. Can be an ArrayIterator, of course
foreach (new LimitIterator($it, 10) as $k => $v) { ... }

Nikita