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<title>[25476] trunk/src/wp-includes/plugin.php: Clean up the documentation for add_filter and apply_filters.</title>
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<dt>Revision</dt> <dd><a href="http://core.trac.wordpress.org/changeset/25476">25476</a></dd>
<dt>Author</dt> <dd>westi</dd>
<dt>Date</dt> <dd>2013-09-18 07:47:31 +0000 (Wed, 18 Sep 2013)</dd>
</dl>
<h3>Log Message</h3>
<pre>Clean up the documentation for add_filter and apply_filters.
Fixes <a href="http://core.trac.wordpress.org/ticket/19203">#19203</a> props DrewAPicture, ericlewis</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunksrcwpincludespluginphp">trunk/src/wp-includes/plugin.php</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="trunksrcwpincludespluginphp"></a>
<div class="modfile"><h4>Modified: trunk/src/wp-includes/plugin.php (25475 => 25476)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/src/wp-includes/plugin.php 2013-09-18 07:41:54 UTC (rev 25475)
+++ trunk/src/wp-includes/plugin.php 2013-09-18 07:47:31 UTC (rev 25476)
</span><span class="lines">@@ -22,47 +22,49 @@
</span><span class="cx"> /**
</span><span class="cx"> * Hooks a function or method to a specific filter action.
</span><span class="cx"> *
</span><del>- * Filters are the hooks that WordPress launches to modify text of various types
- * before adding it to the database or sending it to the browser screen. Plugins
- * can specify that one or more of its PHP functions is executed to
- * modify specific types of text at these times, using the Filter API.
</del><ins>+ * WordPress offers filter hooks to allow plugins to modify
+ * various types of internal data at runtime.
</ins><span class="cx"> *
</span><del>- * To use the API, the following code should be used to bind a callback to the
- * filter.
</del><ins>+ * A plugin can modify data by binding a callback to a filter hook. When the filter
+ * is later applied, each bound callback is run in order of priority, and given
+ * the opportunity to modify a value by returning a new value.
</ins><span class="cx"> *
</span><ins>+ * The following example shows how a callback function is bound to a filter hook.
+ * Note that $example is passed to the callback, (maybe) modified, then returned:
+ *
</ins><span class="cx"> * <code>
</span><del>- * function example_hook($example) { echo $example; }
- * add_filter('example_filter', 'example_hook');
</del><ins>+ * function example_callback( $example ) {
+ * // Maybe modify $example in some way
+ * return $example;
+ * }
+ * add_filter( 'example_filter', 'example_callback' );
</ins><span class="cx"> * </code>
</span><span class="cx"> *
</span><del>- * In WordPress 1.5.1+, hooked functions can take extra arguments that are set
- * when the matching do_action() or apply_filters() call is run. The
- * $accepted_args allow for calling functions only when the number of args
- * match. Hooked functions can take extra arguments that are set when the
- * matching do_action() or apply_filters() call is run. For example, the action
- * comment_id_not_found will pass any functions that hook onto it the ID of the
- * requested comment.
</del><ins>+ * Since WordPress 1.5.1, bound callbacks can take as many arguments as are
+ * passed as parameters in the corresponding apply_filters() call. The $accepted_args
+ * parameter allows for calling functions only when the number of args match.
</ins><span class="cx"> *
</span><del>- * <strong>Note:</strong> the function will return true no matter if the
- * function was hooked fails or not. There are no checks for whether the
- * function exists beforehand and no checks to whether the <tt>$function_to_add</tt>
- * is even a string. It is up to you to take care and this is done for
- * optimization purposes, so everything is as quick as possible.
</del><ins>+ * <strong>Note:</strong> the function will return true whether or not the callback
+ * is valid. It is up to you to take care. This is done for optimization purposes,
+ * so everything is as quick as possible.
</ins><span class="cx"> *
</span><span class="cx"> * @package WordPress
</span><span class="cx"> * @subpackage Plugin
</span><del>- * @since 0.71
- * @global array $wp_filter Stores all of the filters added in the form of
- * wp_filter['tag']['array of priorities']['array of functions serialized']['array of ['array (functions, accepted_args)']']
</del><ins>+ *
+ * @global array $wp_filter A multidimensional array of all hooks and the callbacks hooked to them.
</ins><span class="cx"> * @global array $merged_filters Tracks the tags that need to be merged for later. If the hook is added, it doesn't need to run through that process.
</span><span class="cx"> *
</span><del>- * @param string $tag The name of the filter to hook the $function_to_add to.
- * @param callback $function_to_add The name of the function to be called when the filter is applied.
- * @param int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
- * @param int $accepted_args optional. The number of arguments the function accept (default 1).
</del><ins>+ * @since 0.71
+ *
+ * @param string $tag The name of the filter to hook the $function_to_add callback to.
+ * @param callback $function_to_add The callback to be run when the filter is applied.
+ * @param int $priority (optional) The order in which the functions associated with a particular action are executed. Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
+ * Default 10.
+ * @param int $accepted_args (optional) The number of arguments the function accepts.
+ * Default 1.
</ins><span class="cx"> * @return boolean true
</span><span class="cx"> */
</span><del>-function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
</del><ins>+function add_filter( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) {
</ins><span class="cx"> global $wp_filter, $merged_filters;
</span><span class="cx">
</span><span class="cx"> $idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority);
</span><span class="lines">@@ -114,27 +116,36 @@
</span><span class="cx"> *
</span><span class="cx"> * The function allows for additional arguments to be added and passed to hooks.
</span><span class="cx"> * <code>
</span><del>- * function example_hook($string, $arg1, $arg2)
- * {
- * //Do stuff
- * return $string;
</del><ins>+ * // Our filter callback function
+ * function example_callback( $string, $arg1, $arg2 ) {
+ * // (maybe) modify $string
+ * return $string;
</ins><span class="cx"> * }
</span><del>- * $value = apply_filters('example_filter', 'filter me', 'arg1', 'arg2');
</del><ins>+ * add_filter( 'example_filter', 'example_callback', 10, 3 );
+ *
+ * // Apply the filters by calling the 'example_callback' function we
+ * // "hooked" to 'example_filter' using the add_filter() function above.
+ * // - 'example_filter' is the filter hook $tag
+ * // - 'filter me' is the value being filtered
+ * // - $arg1 and $arg2 are the additional arguments passed to the callback.
+ * $value = apply_filters( 'example_filter', 'filter me', $arg1, $arg2 );
</ins><span class="cx"> * </code>
</span><span class="cx"> *
</span><span class="cx"> * @package WordPress
</span><span class="cx"> * @subpackage Plugin
</span><del>- * @since 0.71
- * @global array $wp_filter Stores all of the filters
- * @global array $merged_filters Merges the filter hooks using this function.
</del><ins>+ *
+ * @global array $wp_filter Stores all of the filters
+ * @global array $merged_filters Merges the filter hooks using this function.
</ins><span class="cx"> * @global array $wp_current_filter stores the list of current filters with the current one last
</span><span class="cx"> *
</span><del>- * @param string $tag The name of the filter hook.
</del><ins>+ * @since 0.71
+ *
+ * @param string $tag The name of the filter hook.
</ins><span class="cx"> * @param mixed $value The value on which the filters hooked to <tt>$tag</tt> are applied on.
</span><del>- * @param mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>.
</del><ins>+ * @param mixed $var Additional variables passed to the functions hooked to <tt>$tag</tt>.
</ins><span class="cx"> * @return mixed The filtered value after all hooked functions are applied to it.
</span><span class="cx"> */
</span><del>-function apply_filters($tag, $value) {
</del><ins>+function apply_filters( $tag, $value ) {
</ins><span class="cx"> global $wp_filter, $merged_filters, $wp_current_filter;
</span><span class="cx">
</span><span class="cx"> $args = array();
</span><span class="lines">@@ -708,7 +719,6 @@
</span><span class="cx"> * @uses $wp_filter Used to process all of the functions in the 'all' hook
</span><span class="cx"> *
</span><span class="cx"> * @param array $args The collected parameters from the hook that was called.
</span><del>- * @param string $hook Optional. The hook name that was used to call the 'all' hook.
</del><span class="cx"> */
</span><span class="cx"> function _wp_call_all_hook($args) {
</span><span class="cx"> global $wp_filter;
</span></span></pre>
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