[wp-trac] [WordPress Trac] #44831: apply_filters_deprecated() and do_action_deprecated() should only trigger a notice when a callback is hooked

[WordPress Trac]

#44831: apply_filters_deprecated() and do_action_deprecated() should only trigger a
notice when a callback is hooked
--------------------------+-------------------------------------
 Reporter:  johnbillion   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Plugins       |    Version:  4.6
 Severity:  normal        |   Keywords:  needs-patch 2nd-opinion
  Focuses:  docs          |
--------------------------+-------------------------------------
 The inline docs for `apply_filters_deprecated()` includes the following
 example code:

 {{{
 // Old filter.
 return apply_filters( 'wpdocs_filter', $value, $extra_arg );

 // Deprecated.
 return apply_filters_deprecated( 'wpdocs_filter', array( $value,
 $extra_arg ), '4.9', 'wpdocs_new_filter' );
 }}}

 The problem with this code is that the deprecated notice is triggered
 regardless of whether a callback is hooked into the deprecated filter or
 not. The deprecated notice should only be triggered if a callback is
 hooked into the filter.

 Two options to fix this. Either:

 1. Update the example code to include a check for
 `has_filter()`/`has_action()`, or
 2. Add a check for `has_filter()`/`has_action()` inside
 `apply_filters_deprecated()`/`do_action_deprecated()` so the notice is
 only triggered when a callback is hooked.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/44831>
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