What does apply_filters(...) actually do in WordPress?

wordpress function
Tim picture Tim · Feb 16, 2010 · Viewed 84.2k times · Source

I'm trying to understand some of the function in WordPress, but I can't get my head around what apply_filters(...) actually does.

Is someone able to clear this up for me with a few examples?

Answer

Richard M picture Richard M · Feb 16, 2010

apply_filters($tag, $value) passes the 'value' argument to each of the functions 'hooked' (using add_filter) into the specified filter 'tag'. Each function performs some processing on the value and returns a modified value to be passed to the next function in the sequence.

For example, by default (in WordPress 2.9) the the_content filter passes the value through the following sequence of functions:

  • wptexturize
  • convert_smilies
  • convert_chars
  • wpautop
  • shortcode_unautop
  • prepend_attachment
  • do_shortcode

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