[wp-trac] [WordPress Trac] #59412: Blocks: Add post-block callback arg to `traverse_and_serialize_block(s)`, change signature

[WordPress Trac]

#59412: Blocks: Add post-block callback arg to `traverse_and_serialize_block(s)`,
change signature
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 Reporter:  Bernhard Reiter  |      Owner:  Bernhard Reiter
     Type:  enhancement      |     Status:  assigned
 Priority:  normal           |  Milestone:  6.4
Component:  General          |    Version:
 Severity:  normal           |   Keywords:
  Focuses:                   |
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 While working on #59399, I [https://github.com/WordPress/wordpress-
 develop/pull/5247#discussion_r1331151853 discovered] that sibling block
 insertion wasn't likely going to work the way I had planned. As a
 consequence, I had to come up with a new way to make it work. This
 requires some changes to `traverse_and_serialize_block(s)`.

 Basically, we need to:
 - Change the signature of the existing callback such that:
   - the function arguments are a ''reference'' to the current block (so it
 can be modified inline, which is important e.g. for `theme` attribute
 insertion), the parent block, and the previous block (instead of the block
 index and chunk index);
   - the return value is a string that will be prepended to the result of
 the inner block traversal and serialization.
 - Add a second callback argument to `traverse_and_serialize_block`, which
 is called _after_ the current inner block is traversed and serialized.
   - Its function arguments are a reference to the current block, the
 parent block, and the next block.

 Its usage is demonstrated in [https://github.com/WordPress/wordpress-
 develop/pull/5261 PR 5261]: The callback arguments are now sufficient to
 insert the serialized hooked blocks as strings, rather than via
 `insert_inner_block`, `prepend_inner block`, or `append_inner_block`. (The
 latter -- which have been introduced only recently, in  [56618] -- are
 thus going to be obsolete.)

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/59412>
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