Re: Convert ext/xml to use an object instead of resource

On Tue, Feb 12, 2019 at 10:00 AM Nikita Popov <nikita.ppv@gmail.com> wrote: > The ext/xml extension currently has GC issues, see > https://bugs.php.net/bug.php?id=76874. The tl;dr is that uses > of > xml_parser > will usually result in a cyclic structure, but resources do not support > cycle GC. This means that the user is required to take care of breaking GC > cycles manually, which is very unusual for PHP. > I would like to port the xml extension from using a resources towards using > an object, which is fully GC integrated. This is implemented in > https://github.com/php/php-src/pull/3526. > > An XmlParser class is used instead of a resource. The class is final and > cannot be manually constructed. It is still used with the normal > xml_parser_* APIs. This is intended as an internal representation change, > not a conversion to OO APIs. The xml_parser_free() method becomes > effectively a no-op and may be deprecated in some future version. > > This change is intended for PHP 7.4. While it is technically BC breaking > (in that code that goes out of the way to use is_resource or similar may > break), but we've done a couple of these resource->object migration in > minor versions in the past (ref > https://wiki.php.net/rfc/operator_overloading_gmp and > https://wiki.php.net/rfc/hash-context.as-resource). > +1 for movement away from resources, generally. Resources represent connections to external resources, in a manner that's opaque to userland [1]. Would it make sense to update is_resource (and friends) to be aware that "resources" returned from xml_parser_* are not resources proper, but rather resources nominal? If userland needed to strictly determine what was a resource proper and what was a resource nominal, we could improve the signature: is_resource(mixed $var, bool $strict = false). But, honestly, the aforementioned opaqueness makes me think this wouldn't be necessary. [1]: http://php.net/manual/en/language.types.resource.php