[wp-trac] [WordPress Trac] #55996: the get_the_block_template_html call all the same functions as the the_conent filter so they are run twice

[WordPress Trac]

#55996: the get_the_block_template_html call all the same functions as the
the_conent filter so they are run twice
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 Reporter:  pbearne                              |       Owner:  flixos90
     Type:  defect (bug)                         |      Status:  assigned
 Priority:  normal                               |   Milestone:  6.4
Component:  Formatting                           |     Version:
 Severity:  normal                               |  Resolution:
 Keywords:  has-patch has-unit-tests changes-    |     Focuses:
  requested                                      |  performance
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Comment (by flixos90):

 Revisiting this ticket, I would like us to take a step back and rethink
 what we want to accomplish here.

 While this ticket is explicitly focused on avoiding duplicate execution of
 certain functions on the same content, I am unsure whether that is what we
 really want, because:
 * There are valid reasons to re-process certain content even if it was
 already processed at another processing layer: For example, a plugin or
 even core itself could implement image loading optimization logic at the
 entire block template level (`template` context) to refine the attributes
 that core otherwise would add at the post content level (`the_content`
 context). Such a thing would not be possible if we were preventing already
 processed content to be re-processed.
 * While it seems undesirable from a performance perspective to process
 certain content multiple times, I don't think it would make a notable
 difference for performance since the processing logic would still need to
 be initialized just as before: For example, to parse blocks at the entire
 block template level, we still need to initialize all the block parsing
 logic even if the post content blocks were already parsed. And there
 wouldn't be any duplication either because already parsed blocks wouldn't
 be reparsed.

 While based on that I lean towards changing course on this ticket, that is
 not to say we just leave it as is. There are certainly some problems that
 result from the double execution that we can solve. Here's a few that were
 brought up before that could be addressed separately:
 * Certain functions like `wptexturize()` or `convert_smilies()` may not be
 desirable for some sites to run, and right now there is no way to remove
 them from the block template level, even when they're being removed from
 `the_content` filter. What we could do here is replace the hard-coded
 function list in `get_the_block_template_html()` with a regular filter and
 callbacks just like in the other cases so that functions can be
 added/removed. [https://github.com/WordPress/wordpress-develop/pull/5188
 See draft pull request]
 * Certain extension points for plugins/themes, such as the
 `wp_content_img_tag` filter, are applied in different contexts and thus
 may process the same content twice which from an API perspective would be
 unexpected and can lead to problems such as an attribute being added
 twice. What we could do here is to use context specific filters so that
 developers wouldn't by accident make certain modifications twice.
 [https://github.com/WordPress/wordpress-develop/pull/5189 See draft pull
 request]

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Ticket URL: <https://core.trac.wordpress.org/ticket/55996#comment:39>
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