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Date: Mon, 17 Aug 2020 19:19:18 +0200
Message-ID: <CAB-BujYLqV+DHEnBhkNikijXzgF+F0r8b4-+jebRqWfc2w9bjw@mail.gmail.com>
To: Mathieu Rochette <mathieu@rochette.cc>
Cc: "PHP internals (internals@lists.php.net)" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Constructor parent property promotion
From: andreas@dqxtech.net (Andreas Hennings)

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Interesting stuff!
https://wiki.php.net/rfc/constructor_promotion
I see this for the first time, but I like it :)

Now to your proposal.
Just to make sure I understand:
Would this map the parameters by name or by index?
-> I assume by index, it makes more sense.
Does it map to parent constructor parameters, or to parent properties?
-> I assume to parent constructor parameters, because parent properties
could be private.
Can the 'parent' parameters be intermixed with other parameters?
-> I assume yes, not allowing it would be an unnecessary limitation.

So if you use the 'parent' syntax, you need exactly as many parameters with
'parent' as required by the parent constructor.

// Parent class
class B {
  public function __construct($b0, $b1) {
    // The values may or may not be written to properties, it does not
matter.
  }
}

// Child class
class C extends B {
  public function __construct(parent $x, private $c0, parent $y, private
$c1) {
    // Implicit: parent::__construct($x, $y);
  }
}




On Mon, 17 Aug 2020 at 18:46, Mathieu Rochette <mathieu@rochette.cc> wrote:

> Hi,
>
>
>
> I=E2=80=99m writing a message here to receive feedback on a two ideas rel=
ated to
> class constructors before going more in details with an RFC. I hope this =
is
> appropriate behavior for this list
>
>
>
> With the Constructor Property Promotion accepted in PHP 8, there=E2=80=99=
s a lot
> less of boilerplate when writing class constructors. I=E2=80=99m suggesti=
ng two
> additional ways of making thing even easier and I hope, readable.
>
>
>
> First: I=E2=80=99d like to be able to automatically transfer a constructo=
r
> property to its parent constructor. I=E2=80=99m thinking of something lik=
e that:
>
>
>
> ```php
>
> class MyCommand extends Command
>
> {
>
>    public function __construct(
>
>        private Connection $connection,
>
>        parent string $name,
>
>    ) {
>
>    }
>
> }
>
> ```
>
>
>
> This would be the equivalent of :
>
>
>
> ```php
>
> class MyCommand extends Command
>
> {
>
>    public function __construct(
>
>        private Connection $connection,
>
>        string $name,
>
>    ) {
>
>        parent::__construct($name);
>
>    }
>
> }
>
> ```
>
>
>
> The second idea is to make the constructor body optional, the first examp=
le
> would now be:
>
>
>
> ```php
>
> class MyCommand extends Command
>
> {
>
>    public function __construct(
>
>        private Connection $connection,
>
>        parent string $name,
>
>    )
>
> }
>
> ```
>
>
>
> This would call the parent constructor automatically even if no "parent"
> parameter are present. I could even see this enforced by linter to avoid
> having logic in the constructors.
>
>
>
> If there is interest I=E2=80=99d like to try writing an rfc and implement=
 it. I
> have not much knowledge of the php-src code but I hope this is a small
> enough change that I=E2=80=99ll be able to tackle. So, at that time if so=
meone is
> interested in mentoring this little project I=E2=80=99d appreciate it :)
>
>
>
>
>
> regards,
>
>
>
> Mathieu

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