Re: [VOTE] Make compact function reports undefined passed variables

The existence of anything that internally relies on get_defined_vars() is a blocker for applying further optimisations to the engine (think stack frames), which is probably why Dmitry suggested its removal. On Sun, 10 Jun 2018, 20:42 Hoffman, Zachary Robert, <zrhoffman@ku.edu> wrote: > >> > >> Hi Gabriel, > >> > >>> compact(), extract(), parse_str() (with 1 argument) and > >>> get_defined_vars() are bad functions, because they access local > variables > >>> indirectly. > >>> > >>> They might be considered to be removed in the next major PHP version, > >>> despite of this fix. > >>> > >>> > >>> Thanks. Dmitry. > >>> > >>> > >> > >> Hello Dmitry. > >> > >> Thanks for this feedback. When I decided to create this RFC adding a > >> warning, many of friends actually suggested me creating an RFC > depracting > >> compact, and complaing with the same arguments as > >> yours. > >> > >> Do you think we should do this already in PHP 7.3? > >> > >> Thanks. > >> > >-- > >Gabriel Caruso > > Deprecating compact() would hurt workflows where you use the same variable > names > several times in different contexts, even though they are only declared > locally > for the purposes of compact() itself. > > Below is an example of what I mean. The array used for compact() is the > same one > that is iterated over outside of class A. Further, we use the variables > that are > compacted earlier in A::c(), so it is convenient to use them as local > variables. > > class A > { > private static $b = [ > 'a', > 'b', > 'c', > 'd', > ]; > > public static function b() > { > return self::$b; > } > > public function d() > { > return 2; > } > > public function c() > { > $d = $this->d(); > $a = pow($d, $d + 1); > $c = $a ^ 0b1100; > $b = $a - $d; > > return new B( > compact( > $this->b() > ) > ); > } > } > > class B > { > private $a; > > public function __construct($a) > { > $this->a = $a; > } > > public function a(string $name) > { > return $this->a[$name]; > } > } > > $a = (new A())->c(); > > foreach (A::b() as $b) { > echo $a->a($b) . PHP_EOL; > } > > The alternative would be manipulating array elements directly, like this: > > public function c() > { > $e['d'] = $this->d(); > $e['a'] = pow($e['d'], $e['d'] + 1); > $e['c'] = $e['a'] ^ 0b1100; > $e['b'] = $e['a'] - $e['d']; > > return new B($e); > } > > That is far more cumbersome. So, compact() has legitimate uses sometimes. > > Cheers, > > -- > Zach Hoffman > ________________________________________ > From: Gabriel Caruso <carusogabriel34@gmail.com> > Sent: Saturday, June 9, 2018 12:25 > To: Dmitry Stogov > Cc: PHP Internals > Subject: Re: [PHP-DEV] [VOTE] Make compact function reports undefined > passed variables > > > > > Hi Gabriel, > > > >> compact(), extract(), parse_str() (with 1 argument) and > >> get_defined_vars() are bad functions, because they access local > variables > >> indirectly. > >> > >> They might be considered to be removed in the next major PHP version, > >> despite of this fix. > >> > >> > >> Thanks. Dmitry. > >> > >> > > > > Hello Dmitry. > > > > Thanks for this feedback. When I decided to create this RFC adding a > > warning, many of friends actually suggested me creating an RFC depracting > > compact, and complaing with the same arguments as yours. > > > > Do you think we should do this already in PHP 7.3? > > > > Thanks. > > > -- > Gabriel Caruso > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >