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Date: Thu, 2 Oct 2025 10:30:37 +0200
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Subject: Re: [PHP-DEV] [DISCUSSION] Validating regex pattern
To: Dennis Snell <dennis.snell@automattic.com>
Cc: PHP internals list <internals@lists.php.net>
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From: alex.daubois+php@gmail.com (Alexandre Daubois)

Hi,

>     function is_valid_preg_pattern( $pattern ) {
>         $is_valid =3D true;
>
>         set_error_handler( function () use ( &$is_valid ) { $is_valid =3D=
 false; return true; }, E_WARNING );
>         preg_match( $pattern, '' );
>         restore_error_handler();
>
>         return $is_valid;
>     }

Setting and restoring the global error handler to validate a pattern
is exactly what I would qualify as clunky/hacky. Also this requires
internal knowledge on how this works, which feels very wrong for
something like that.

=E2=80=94 Alexandre Daubois