Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:124458
Feedback-ID: i8414410d:Fastmail
User-Agent: Cyrus-JMAP/3.11.0-alpha0-568-g843fbadbe-fm-20240701.003-g843fbadb
Precedence: bulk
MIME-Version: 1.0
Message-ID: <798adb8d-ae06-49a7-bf2b-fd0037a374c0@app.fastmail.com>
In-Reply-To: <356aa359-e109-4b2f-82e2-e15fcaf0c64d@scriptfusion.com>
References: <5bdbffef-4954-415d-9dae-4c9bd4ba0f22@scriptfusion.com>
 <CAAKU0u=JNHNkhcCxOQ3fzY9Eu1xiQoyb3fNPJgHtY9P6jYxn0A@mail.gmail.com>
 <356aa359-e109-4b2f-82e2-e15fcaf0c64d@scriptfusion.com>
Date: Wed, 17 Jul 2024 14:01:55 +0000
To: "php internals" <internals@lists.php.net>
Subject: Re: [PHP-DEV] array_reduce callback key
Content-Type: text/plain
From: larry@garfieldtech.com ("Larry Garfield")

On Wed, Jul 17, 2024, at 9:01 AM, Bilge wrote:
> On 17/07/2024 01:41, Levi Morrison wrote:
>> Adding arguments to a function can mess up internal callbacks, btw, so I don't like modifying the
>> existing function.
> Which internal callbacks can be messed up by this change? They clearly 
> aren't tested, as the build is passing.
>
> Cheers,
> Bilge

There's a number of issues here.

PHP-defined functions ignore excess arguments.

C-defined functions error on excess arguments.

A function with an optional second argument... may break if it gets passed an optional argument that isn't aligned with its expectation.  intval() is the usual example (https://www.php.net/intval), but it would also impact something like trim().  If someone is using a function with one param and one optional param as a callback right now, suddenly passing the key as the second argument could cause all sorts of weirdness.

Similarly, if someone is using a single-param C-defined function as a callback right now, and array_reduce() starts passing a second argument, it will fatal.

I ran into this issue while building Crell/fp, and my only solution (after swearing a lot) was to just make two separate versions of every operation: One that passes the key and one that doesn't.  (cf: https://github.com/Crell/fp/blob/master/src/array.php)  The user has to pick the right one.  That is, sadly, the only reliable solution, even if done in the stdlib.

(Of course, the real solution is to introduce a separate map/dict type that has its own dedicated API for map/filter/reduce, but now we're well out of scope...  Using the same structure for lists and maps is PHP's original sin.)

--Larry Garfield