HTML Processor: ::create_fragment returns self when subclassed

[jonsurrell]

In a subclass of WP_HTML_Processor when an instance is created from the static ::create_fragment method the instance will be an instance of WP_HTML_Processor and not and instance of the subclass:

<?php
class Sub extends WP_HTML_Processor {}
$processor = Sub::create_fragment( '<div>' );
get_class( $processor ); // "WP_HTML_Processor" !!

It's very unlikely that the parent class instance is intended to be created from the subclass.

This can be fixed by creating static from the ::create_fragment method.

In a subclass of WP_HTML_Processor when an instance is created from the static ::create_fragment method the instance will be an instance of WP_HTML_Processor and _not_ and instance of the subclass:

class Sub extends WP_HTML_Processor {}
$processor = Sub::create_fragment( '<div>' );
get_class( $processor ); // "WP_HTML_Processor" !!

It's very unlikely that the parent class instance is intended to be created from the subclass.

Trac ticket: https://core.trac.wordpress.org/ticket/61374

Trac ticket: Core-61374

In a subclass of WP_HTML_Processor when an instance is created from the static ::create_fragment method the instance will be an instance of WP_HTML_Processor and _not_ and instance of the subclass:

class Sub extends WP_HTML_Processor {}
$processor = Sub::create_fragment( '<div>' );
get_class( $processor ); // "WP_HTML_Processor" !!

It's very unlikely that the parent class instance is intended to be created from the subclass.

[dmsnell]

In 58363:

HTML API: Return subclass from ::create_fragment

When the WP_HTML_Processor was introduced with its ::create_fragment()
static creator method, that method has been returning a new self(...).
Unfortunately, this means that subclasses cannot use that method since it
will return the WP_HTML_Processor instead of the subclass.

With this patch, the static creator method returns new static(...) to preserve
the intended behavior. A new test asserts this behavior for future changes.

Developed in ​https://github.com/WordPress/wordpress-develop/pull/6729
Discussed in https://core.trac.wordpress.org/ticket/61374

Props dmsnell, jonsurrell.
Follow-up to [56274].
Fixes #61374.

Merged in [58363]
​https://github.com/wordpress/wordpress-develop/commit/0cad031a5afb33567b219ffcaeb62dfff6bd0936

Trac ticket: Core-61374

In a subclass of WP_HTML_Processor when an instance is created from the static ::create_fragment method the instance will be an instance of WP_HTML_Processor and _not_ and instance of the subclass:

class Sub extends WP_HTML_Processor {}
$processor = Sub::create_fragment( '<div>' );
get_class( $processor ); // "WP_HTML_Processor" !!

It's very unlikely that the parent class instance is intended to be created from the subclass.