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Date: Thu, 12 Jan 2017 22:34:44 +0100
In-Reply-To: <CADyq6sJojHOKQ_CJvKGuBC9XrSAkoxGyi52=QjgFHHhzW+KFow@mail.gmail.com>
Cc: PHP Internals <internals@lists.php.net>
To: Marco Pivetta <ocramius@gmail.com>
References: <0DE25BF8-D349-48EF-A83B-8837DD4AD1E0@gmail.com>
 <CADyq6sJojHOKQ_CJvKGuBC9XrSAkoxGyi52=QjgFHHhzW+KFow@mail.gmail.com>
Subject: Re: [PHP-DEV] Explicit constructor call and polymorphic dispatch
From: tim.bezhashvyly@gmail.com (Tim Bezhashvyly)

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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:
>=20
> Heya,
>=20
> While I agree that it is weird to be able to call constructors more =
than once, this is generally used for:
>=20
>  * lazy loading
>  * resource reset
>=20
> Specifically, what is going on is something like following:<?php
>=20
> final class DbConnection
> {
>     private $dsn;
>     private $initializer;
>     public function __construct(string $dsn)
>     {
>         $this->dsn =3D $dsn;
>         // socket stuff happens here, much like with PDO
>     }
>=20
>     public function query(string $queryString) : array
>     {
>         ($this->initializer)();
>         // irrelevant from here on
>         return ['query' =3D> $queryString, 'dsn' =3D> $this->dsn];
>     }
>=20
>     public static function lazyInstance(string $dsn) : self
>     {
>         $instance =3D (new =
ReflectionClass(self::class))->newInstanceWithoutConstructor();
>         $instance->initializer =3D function () use ($dsn, $instance) {
>             $instance->__construct($dsn);
>             $instance->initializer =3D function () {
>             };
>         };
>         return $instance;
>     }
> }
>=20
> $instance =3D DbConnection::lazyInstance('mysql://something');
>=20
> var_dump($instance);
>=20
> var_dump($instance->query('SELECT * FROM foo'));
> var_dump($instance->query('SELECT * FROM bar'));
>=20
> Here's an example of it at work: https://3v4l.org/Y0eoL =
<https://3v4l.org/Y0eoL>
>=20
> The pattern is simple:
>=20
>  * intercept constructor call
>  * capture constructor parameters
>  * instantiate without constructor
>  * defer constructor call for later
>=20
> 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).
>=20
> Therefore I don't see a reason to drop manual constructor calls, =
unless there is a strong necessity to get rid of 'em.
>=20
>=20
>=20
> Marco Pivetta=20
>=20
> http://twitter.com/Ocramius <http://twitter.com/Ocramius>     =20
>=20
> http://ocramius.github.com/ <http://ocramius.github.com/>
>=20
> On Thu, Jan 12, 2017 at 8:11 AM, Tim Bezhashvyly =
<tim.bezhashvyly@gmail.com <mailto:tim.bezhashvyly@gmail.com>> wrote:
> Dear internals,
>=20
> I would like to propose 2 RFCs:
>=20
> - Disallow explicit call of __construct method
> - Polymorphic dispatch
>=20
> 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.
>=20
> Otherwise please bless me with mana which will allow me to submit =
them.
>=20
> Regards,
> Tim
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> To unsubscribe, visit: http://www.php.net/unsub.php =
<http://www.php.net/unsub.php>
>=20
>=20


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