你有all 例如，在此函数中解释
File: wp-includes/plugin.php
402: /**
403: * Execute functions hooked on a specific action hook.
404: *
405: * This function invokes all functions attached to action hook `$tag`. It is
406: * possible to create new action hooks by simply calling this function,
407: * specifying the name of the new hook using the `$tag` parameter.
408: *
409: * You can pass extra arguments to the hooks, much like you can with apply_filters().
410: *
411: * @since 1.2.0
412: *
413: * @global array $wp_filter Stores all of the filters
414: * @global array $wp_actions Increments the amount of times action was triggered.
415: * @global array $wp_current_filter Stores the list of current filters with the current one last
416: *
417: * @param string $tag The name of the action to be executed.
418: * @param mixed $arg,... Optional. Additional arguments which are passed on to the
419: * functions hooked to the action. Default empty.
420: */
421: function do_action($tag, $arg = \'\') {
422: global $wp_filter, $wp_actions, $wp_current_filter;
423:
424: if ( ! isset($wp_actions[$tag]) )
425: $wp_actions[$tag] = 1;
426: else
427: ++$wp_actions[$tag];
428:
429: // Do \'all\' actions first
430: if ( isset($wp_filter[\'all\']) ) {
431: $wp_current_filter[] = $tag;
432: $all_args = func_get_args();
433: _wp_call_all_hook($all_args);
434: }
435:
436: if ( !isset($wp_filter[$tag]) ) {
437: if ( isset($wp_filter[\'all\']) )
438: array_pop($wp_current_filter);
439: return;
440: }
441:
442: if ( !isset($wp_filter[\'all\']) )
443: $wp_current_filter[] = $tag;
444:
445: $args = array();
446: if ( is_array($arg) && 1 == count($arg) && isset($arg[0]) && is_object($arg[0]) ) // array(&$this)
447: $args[] =& $arg[0];
448: else
449: $args[] = $arg;
450: for ( $a = 2, $num = func_num_args(); $a < $num; $a++ )
451: $args[] = func_get_arg($a);
452:
453: $wp_filter[ $tag ]->do_action( $args );
454:
455: array_pop($wp_current_filter);
456: }
该部分：
429: // Do \'all\' actions first
说话
all 具有特殊处理内钩生成器功能。
您将在其他挂钩生成器功能中找到类似的逻辑：
apply_filters
apply_filters_ref_array
apply_filters_deprecated
do_action
do_action_ref_array
do_action_deprecated
所以
all 有特殊待遇。
您可以使用all 用于内省，如here 其中，我按顺序列出了单个WordPress请求的所有操作挂钩。
从评论中：我理解，但我想知道WordPress如何理解，当传递这个键时，它会影响所有操作或过滤器。应该在某个地方定义
我花了一些时间才明白你的意思。对有一个叫做$wp_filter 所有挂钩都保存在那里。在示例中add_action( \'all\', \'_20161224_printer\' ); here, 这将在全球范围内。
[all] => WP_Hook Object
(
[callbacks] => Array
(
[10] => Array
(
[_20161224_printer] => Array
(
[function] => _20161224_printer
[accepted_args] => 1
)
)
)
[iterations:WP_Hook:private] => Array
(
)
[current_priority:WP_Hook:private] => Array
(
)
[nesting_level:WP_Hook:private] => 0
[doing_action:WP_Hook:private] =>
)
