Re: Explicit constructor call and polymorphic dispatch

Hi Marco, the only reason for prohibiting explicit __construct calls is that it makes PHP objects mutable and it's state unpredictable. Still would like to give this RFC a try. And what about polymorphic dispatch? Regards, Tim > On 12 Jan 2017, at 21:35, Marco Pivetta <ocramius@gmail.com> wrote: > > Heya, > > While I agree that it is weird to be able to call constructors more than once, this is > generally used for: > > * lazy loading > * resource reset > > Specifically, what is going on is something like following:<?php > > final class DbConnection > { > private $dsn; > private $initializer; > public function __construct(string $dsn) > { > $this->dsn = $dsn; > // socket stuff happens here, much like with PDO > } > > public function query(string $queryString) : array > { > ($this->initializer)(); > // irrelevant from here on > return ['query' => $queryString, 'dsn' => $this->dsn]; > } > > public static function lazyInstance(string $dsn) : self > { > $instance = (new ReflectionClass(self::class))->newInstanceWithoutConstructor(); > $instance->initializer = function () use ($dsn, $instance) { > $instance->__construct($dsn); > $instance->initializer = function () { > }; > }; > return $instance; > } > } > > $instance = DbConnection::lazyInstance('mysql://something'); > > var_dump($instance); > > var_dump($instance->query('SELECT * FROM foo')); > var_dump($instance->query('SELECT * FROM bar')); > > Here's an example of it at work: https://3v4l.org/Y0eoL > <https://3v4l.org/Y0eoL> > > The pattern is simple: > > * intercept constructor call > * capture constructor parameters > * instantiate without constructor > * defer constructor call for later > > The same can be used in a myriad of different ways, but this is a legit use-cases that > generally don't involve coding everything into the same class (and I generally advise against > doing that anyway). > > Therefore I don't see a reason to drop manual constructor calls, unless there is a strong > necessity to get rid of 'em. > > > > Marco Pivetta > > http://twitter.com/Ocramius > <http://twitter.com/Ocramius> > > http://ocramius.github.com/ > <http://ocramius.github.com/> > > On Thu, Jan 12, 2017 at 8:11 AM, Tim Bezhashvyly <tim.bezhashvyly@gmail.com > <mailto:tim.bezhashvyly@gmail.com>> wrote: > Dear internals, > > I would like to propose 2 RFCs: > > - Disallow explicit call of __construct method > - Polymorphic dispatch > > I'm sure I'm not the first who came with those 2 ideas so in case those were already > proposed and rejected just let me know. > > Otherwise please bless me with mana which will allow me to submit them. > > Regards, > Tim > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > <http://www.php.net/unsub.php> > >