It was on design. list() was intended to support plain arrays only. Thanks. Dmitry.
On Fri, Sep 26, 2014 at 12:45 AM, Nikita Popov <nikita....@gmail.com> wrote: > On Thu, Sep 25, 2014 at 10:32 PM, Nikita Popov <nikita....@gmail.com> > wrote: > >> On Thu, Sep 25, 2014 at 1:15 PM, Dmitry Stogov <dmi...@zend.com> wrote: >> >>> disabling string handling would allow make operation simpler and would >>> improve regular access to array elements. >>> We won't need to check for (opline->extended_value & ZEND_FETCH_ADD_LOCK) >>> in FETCH_DIM_R handler. >>> However, it's going to be very small improvement, and I don't care a >>> lot. :) >>> >>> enabling string handling would require complication of >>> ZEND_FETCH_DIM_TMP_VAR handler (for strings support). >>> It's going to make list() handling a bit slower, but not significantly. >>> >>> my choice +1 for disabling. >>> >> >> Could you please clarify why removing string support would make the >> operation simpler? I voted for always supporting strings because I thought >> that is the option that simplifies things - in particular it would allow >> use to drop the FETCH_DIM_TMP_VAR opcode and always go through FETCH_DIM_R >> instead. Sample patch here: >> https://github.com/nikic/php-src/compare/stringOffsetsInList Or did I >> miss something and we can't do that? >> >> Nikita >> > > I'd like to add that the FETCH_DIM_TMP_VAR opcode also provides incorrect > results if objects are used. list() generally accepts objects implementing > ArrayAccess, but if the object happens to be a TMP_VAR and > FETCH_DIM_TMP_VAR is used instead of FETCH_DIM_R, you'll just get a NULL > result: > > <?php > > class Arr implements ArrayAccess { > private $arr; > public function offsetGet($k) { return $this->arr[$k]; } > public function offsetSet($k, $v) { $this->arr[$k] = $v; } > public function offsetExists($k) { return isset($this->arr[$k]); } > public function offsetUnset($k) { unset($this->arr[$k]); } > } > > $arr = new Arr; > $arr[0] = 'foo'; > $arr[1] = 'bar'; > > list($a, $b) = $arr; > var_dump($a, $b); // foo, bar > > // (object) forces TMP_VAR > list($a, $b) = (object) $arr; > var_dump($a, $b); // NULL, NULL > > So to handle that case we'd already have to extend the FETCH_DIM_TMP_VAR > handler to support objects in addition to arrays. At which point I don't > really see the point of making this a special case and would always use > FETCH_DIM_R instead (which already has all the necessary code to support > arrays, objects and strings). > > Nikita >
