[wp-trac] [WordPress Trac] #23347: Theme fallbacks for post format meta data

[WordPress Trac]

#23347: Theme fallbacks for post format meta data
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 Reporter:  helen        |       Owner:
     Type:  enhancement  |      Status:  new
 Priority:  normal       |   Milestone:  3.6
Component:  Template     |     Version:
 Severity:  normal       |  Resolution:
 Keywords:  has-patch    |
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Comment (by nacin):

 == The Different Situations ==

 '''Three theme situations:'''
   1. Theme doesn't support post formats
   2. Theme supports old-style post formats
   3. Theme supports new-style "structured" post formats

 '''A — Three fallback situations:'''
   1. Theme does not support a format, but the post has new-style
 "structured" post format data
    * '''Fallback:''' Turn new-style structured data into HTML and use
 the_content filter
   2. Theme supports a format (old-style), but the post has new-style
 "structured" post format data
    * '''Fallback:''' Turn new-style structured data into HTML and use
 the_content filter
   3. Theme supports a format (new-style), but the post has old-style
 unstructured post content
    * '''Fallback:''' Parse out post_content into individual pieces of post
 format data. (This needs to occur, because this theme wouldn't necessarily
 have a call to the_content() for all post formats, would it?)

 '''B — Three situations where do not 'fall back':'''
   1. Theme does not support a post format, and the post has old-style
 unstructured post content
   2. The theme supports a format (old-style), and the post has old-style
 unstructured post content
   3. Theme supports a format (new-style), and the post has new-style post
 format data

 To reorganize these content situations based on the individual theme
 situations: (someone can turn this into a flowchart if they'd like)

  1. Theme doesn't support a post format:
   * The post has new-style "structured" post format data. '''Fallback:'''
 Turn it into HTML, use the_content.
   * The post has old-style post content: Do nothing.
  2. Theme supports a post format, old-style:
   * The post has new-style post format data: '''Fallback:''' Turn it into
 HTML, use the_content.
   * The post has old-style post content: Do nothing.
  3. The theme supports a post format, new-style:
   * The post has new-style post-format data: Do nothing.
   * The post has old-style post content: '''Fallback:''' Parse
 post_content into pieces of post format data.

 == Old versus New Formats ==

 It is clear here that a theme not supporting a format is pretty much the
 same as supporting old-style formats. This is even more apparently now
 that we will be allowing a user to use any formats they wish, even if the
 theme does not support it, so the old-style "support" becomes pretty close
 to meaningless.

 Also, since each format is individually supported or not supported, you
 could have many of these situations occurring on the same site, without a
 teme switch:

  * '''A theme supports the quote format, with new-style structured data'''
 (B3)
  * The site also has chat posts written with metadata (A1 — must convert
 these into HTML)
  * The site has link formats without metadata (B1 — show these as-is)
  * It also has old-style quotes (A3 — must parse these into pieces)

 Or:

  * '''A theme supports the quote format, old-style''' (B2)
  * The site has quote formats written with metadata (A2 — must convert
 these into HTML)
  * The site has chat posts written with metadata (A1 — must convert these
 into HTML)
  * The site has chat posts written without metadata (B1)

 == Theme Support ==

 It is probably apparent by now that we need to know when a theme supports
 a new-style format in particular. Whether the theme supports an old-style
 format in only has to do with whether the theme has a particular design
 for that format, and isn't very helpful anymore.

 To make this change, I suggest we come up with a new theme support
 argument. Specifically, structured-post-formats:

 {{{
 add_theme_support( 'structured-post-formats', array( 'quote' ) );
 }}}

 This would replace post-formats support. It is a trivial change, but would
 be necessary because themes would have to make bigger changes anyway —
 specifically, switch to new template tags to support the new-style
 metadata.

 Under the hood, we could automatically register support for post-formats
 when structured-post-formats is registered. Then you can have checks like
 `current_theme_supports( 'post-formats' ) && ! current_theme_supports(
 'structured-post-formats' )` to see if a theme supports post formats
 generally, but not the newer structured ones. (Note that I would prevent
 in code the ability for a theme to say "Yes I support these formats" with
 some being old-style, others being new-style. As said above, there is no
 purpose for this — in terms of working with content, supporting old-style
 is the same as not having the format supported at all. So it is best to
 avoid such an API rift.)

 == Compatibility Across WordPress Versions ==

 If a theme wishes to remain compatible with 3.5 while still supporting 3.6
 methods, they'll need to do a few things. (I would recommend doing this
 for Twenty Ten and Twenty Eleven, and leaving Twenty Twelve for 3.6+ only,
 to set different examples and to keep 3.6 clean. Supporting forward for an
 older theme is important; supporting backward for a newer theme is not.)

  1. They'd need to call add_theme_support() for both post-formats and
 structured-post-formats. The former would get ignored in 3.6, the latter
 would get ignored in 3.5.

  2. They'd need to function_exists( 'get_post_format_meta' ) before using
 the new-style functions. In their `else`, they'd use the_content() as
 before.

 == Feeds ==

 One final note, everything goes out the window when dealing with an RSS
 feed. Everything needs to be piped back into the_content(). `is_feed()`
 does not appear to be accounted for in [23450].

-- 
Ticket URL: <http://core.trac.wordpress.org/ticket/23347#comment:25>
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