Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:110954
MIME-Version: 1.0
References: <CAJpLVh3VjCV4kR4n2EGnfYx8J6zQ7FafG7Q6kdbQ0HEMxZHMmw@mail.gmail.com>
In-Reply-To: <CAJpLVh3VjCV4kR4n2EGnfYx8J6zQ7FafG7Q6kdbQ0HEMxZHMmw@mail.gmail.com>
Date: Sat, 11 Jul 2020 21:22:18 +0200
Message-ID: <CADyq6sLLE7W5vReeS1wGdQFdtSexcO5yEUi6gnkFGYGHtdkA6w@mail.gmail.com>
To: =?UTF-8?Q?Olle_H=C3=A4rstedt?= <olleharstedt@gmail.com>
Cc: PHP Internals List <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000e9e34f05aa2f60b3"
Subject: Re: [PHP-DEV] Possible RFC: UniqueInterface that throws exception at
 refcount > 1
From: ocramius@gmail.com (Marco Pivetta)

--000000000000e9e34f05aa2f60b3
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Hey Olle,

On Sat, Jul 11, 2020 at 4:06 PM Olle H=C3=A4rstedt <olleharstedt@gmail.com>
wrote:

> Dear internals,
>
> I'd like to discuss the concept of ownership in PHP, from the point of
> view of a new interface UniqueInterface (or SplUniqueInterface or
> something), which will throw a UniqueException if refcount > 1.
>
> Use-case: Mutable objects that cannot be shared (without (deep) cloning).
>
> Rational: Immutable objects are considered "easier to reason about"
> and generally more safe, and as a way to avoid
> spooky-action-at-a-distance. I argue that mutability is totally fine
> as long as it's not *being shared*. Currently, there's no way to
> enforce this in PHP, *but* PHP has a refcounting GC which could do
> this. This would be a more performant alternative than to build lots
> of immutable objects using $obj->whereSomething('bla') constructs.
>
> Cons: If PHP switches to tracing GC, it will be unusable.
>
> What do you think? Should I write it down as an RFC? Implementation
> should be straight-forward, assuming refcount is manipulated at a
> single place in the source.
>
> Regards
> Olle
>

I consider the problem problem of singleton enforcement to be solved
elegantly in userland, such as in
https://github.com/marc-mabe/php-enum/blob/v4.3.0/src/Enum.php

Considering that, what does a language-level construct bring in?

Marco Pivetta

http://twitter.com/Ocramius

http://ocramius.github.com/

--000000000000e9e34f05aa2f60b3--