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Date: Fri, 8 Sep 2023 15:35:10 +0200
Message-ID: <CAPzBOBOn3DCno71k_COPMjjw4sff70vxazqJgAPQbB0wW3BvNQ@mail.gmail.com>
To: Lanre Waju <lanre@online-presence.ca>
Cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] RFC Proposal: Readonly Structs in PHP
From: landers.robert@gmail.com (Robert Landers)

On Fri, Sep 8, 2023 at 3:12=E2=80=AFPM Lanre Waju <lanre@online-presence.ca=
> wrote:
>
> Dear PHP Internals,
>
> I am writing to propose a new feature for PHP that introduces the
> concept of structs. This feature aims to provide a more concise and
> expressive way to define and work with immutable data structures. Below
> is a detailed description of the proposed syntax, usage, and behavior.
>
> Syntax
>
> struct Data
> {
>      string $title;
>      Status $status;
>      ?DateTimeImmutable $publishedAt =3D null;
> }
> The Data struct is essentially represented as a readonly class with a
> constructor as follows:
>
>
> readonly class Data
> {
>      public function __construct(
>          public string $title,
>          public Status $status,
>          public ?DateTimeImmutable $publishedAt =3D null,
>      ) {}
> }
> Assertions
> The Data struct will always be readonly.
> It has no methods besides the constructor.
> Constructors
> The Data struct can be constructed in three different ways, each of
> which allows for named or positional arguments, which can be mixed:
>
> 1.1 Class like
> $data =3D new Data('title', Status::PUBLISHED, new DateTimeImmutable());
>
> 1.2 Class like (Named Syntax)
> $data =3D new Data(title: 'title', status: Status::PUBLISHED, publishedAt=
:
> new DateTimeImmutable());
>
> 2.1 Proposed struct initialization syntax (Positional Arguments)
> $data =3D Data{'title', Status::PUBLISHED, new DateTimeImmutable()};
>
> 2.2 Proposed struct initialization syntax (Named Syntax)
> $data =3D Data{title: 'title', status: Status::PUBLISHED, publishedAt: ne=
w
> DateTimeImmutable()};
>
> 3.1 Anonymous Struct (Named Arguments)
>
> $data =3D struct {
>      string $title;
>      Status $status;
>      ?DateTimeImmutable $publishedAt =3D null;
> }('title', Status::PUBLISHED, new DateTimeImmutable());
> 3.2 Anonymous Struct (Named Arguments - Named Syntax)
>
> $data =3D struct {
>      string $title;
>      Status $status;
>      ?DateTimeImmutable $publishedAt =3D null;
> }(title: 'title', status: Status::PUBLISHED, publishedAt: new
> DateTimeImmutable());
> Nesting
> The proposed feature also supports nesting of structs. For example:
>
>
> final class HasNestedStruct
> {
>      NestedStruct {
>          string $title;
>          Status $status;
>          ?DateTimeImmutable $publishedAt =3D null;
>      };
>
>      public function __construct(
>          public string $string,
>          public Data $normalStruct,
>          public NestedStruct $nestedStruct =3D NestedStruct{'title',
> Status::PUBLISHED, new DateTimeImmutable()},
>          public struct InlineNamed { int $x} $inlineNamed =3D {x: 1},
>          public { int $x, int $y} $inlineAnonymous =3D {x: 1, y: 2},
>      ) {}
> }
> This proposal aims to enhance the readability and maintainability of
> code by providing a more concise and expressive way to work with
> immutable data structures in PHP.
> I believe this feature will be a valuable addition to the language as it
> not only opens the door for future enhancements (eg. typed json
> deserialization, etc.), but should also help reduce reliance on arrays
> by providing a more expressive alternative.
>
> Your feedback and suggestions are highly appreciated, and we look
> forward to discussing this proposal further within the PHP internals
> community.
>
> Sincerely
> Lanre
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: https://www.php.net/unsub.php
>

FWIW (and it isn't worth much), I'm not a fan of the braces styles
(2.1, 2.2) as it is very non-php-ish.

It'd be great to still have methods, e.g., $data->isAfter($date) or
something. Otherwise, it isn't very useful except as typed arrays,
without any of the usefulness of the array functions.

Also, what if I want a new $data object but with slightly different
property values?