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Date: Mon, 24 Feb 2020 08:18:54 +0000
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To: internals@lists.php.net
Message-ID: <135A46A4-9210-4FDF-AD48-460F3F7B14AC@gmail.com>
Subject: Re: [PHP-DEV] [RFC] [DISCUSSION] Immutable/final/readonly properties
From: rowan.collins@gmail.com (Rowan Tommins)

On 24 February 2020 03:26:19 GMT+00:00, Marco Pivetta <ocramius@gmail=2Ecom=
> wrote:
>The solution is trivial: don't use cloning:
>
>final class Foo
>{
>    public function withBar($bar):self {
>        $instance =3D new self();
>        $instance->foo =3D $foo;
>        // more assignments here - unavoidable
>        return $instance;
>    }
>}


This works fine on paper, but is completely impractical as the class grows=
=2E Consider a class with 10 such properties, each with their own with* met=
hod: switching from clone to explicit assignments means adding 90 lines of =
code, all of it copy-and-pasted boilerplate that's hard to spot mistakes in=
=2E

It's also impossible to use with inheritance, or to compose with traits (a=
s Diactoros does, for instance), because every with* method needs to know t=
he full details of how to create a partial clone=2E

Regards,

--=20
Rowan Tommins
[IMSoP]