This allows shortcodes to perform more complex actions on the element
which contains them. For example, the element reference can be used
to add extra classes or attributes to links which provide additional
metadata.
Since that used to be the default shortcode notation
for our core "insert media" functionality, its important
to have this fixed and keep supporting "legacy" content
created with 3.0.
Shortcodes have traditionally had a problem that they are inside <p> tags,
but generate block level elements. This breaks HTML compliance.
This makes the shortcode parser now mutate the DOM based on the "class" attribute on
the shortcode to insert the generated block level element at the right place in the DOM
- for "left" and "right" elements it puts them just before the block level
element they are inside
- for "leftAlone" and "center" elements it splits the DOM around the shortcode.
The trade off is that shortcodes are no longer "text level" features. They need
knowledge of the HTML they are in to perform this transformation, so they can
only be used in (valid) HTML
The entire framework repo (with the exception of system-generated files) has been amended to respect the 120c line-length limit. This is in preparation for the enforcement of this rule with PHP_CodeSniffer.
