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Date: Sun, 25 Apr 2021 17:09:00 -0400
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To: David Rodrigues <david.proweb@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Method overload support
From: matthewmatthew@gmail.com (Matthew Brown)

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On Sun, 25 Apr 2021 at 16:12, David Rodrigues <david.proweb@gmail.com>
wrote:

> I know that this discussion comes back from time to time, but now that PHP
> is quite strong in relation to argument typing, I think it is worthwhile to
> have a quick discussion about it. Maybe to PHP 9.
>
> One of the things I remember that was a big problem was the performance
> impact in determining what the ideal method would be, without testing it
> each time.
>
> 1. The test only needs to happen for overloaded methods. So, most of the
> time, no change will occur.
>
> 2. Opcache may be able to help indicate which method will be executed, when
> it is available. And perhaps, in some situations, it is possible to
> determine which method will be tested as a priority, without having to test
> all the time (in a loop, for example).
>
> function printId(User $user) { return a($user->id); }
> function printId(int $userId) { printf($userId); }
>
> foreach ([1, 2, 3, 4, $userInstance] as $userId) {
>     printId($userId);
>     // First time:
>     // 1. Overload detected, but the best option is unknown;
>     // 2. Test option #1: rejected;
>     // 3. Test option #2: accepted and used;
>     // Next times:
>     // 1. Overload detected, the last occurrence was option #2, accepted
> and used;
>     // 2. Option #2 can't be used for $userInstance, retest all options
> (except #2).
> }
>
> 3. Poorly typed functions or methods cannot be overloaded.
>
> function printId(User $user) { ... }
> function printId($user) { ... } // Fatal error
>
>
> Atenciosamente,
> David Rodrigues
>

This was brought up four years ago (https://externals.io/message/93831) and
you brought this up two years ago, but I don't think anything has changed
to change the answer.

The responses in the four-years-ago post contain some good explanations.
Unless you have a draft implementation that fixes the issues mentioned I'm
not sure it's productive to bring it up again.

Best wishes,

Matt

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