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событие не описано

loop_start хук-событие . WP 2.0.0

Fires once the loop is started.

Использование

add_action( 'loop_start', 'action_function_name_4268' );
function action_function_name_4268( $this ){
	// action...
}
$this(WP_Query)
The WP_Query instance (passed by reference).

Где используется хук

Код хука

Фрагмент из: wp-includes/class-wp-query.php VER 4.9.8
...
	 *
	 * @global WP_Post $post
	 */
	public function the_post() {
		global $post;
		$this->in_the_loop = true;

		if ( $this->current_post == -1 ) // loop has just started
			/**
			 * Fires once the loop is started.
			 *
			 * @since 2.0.0
			 *
			 * @param WP_Query $this The WP_Query instance (passed by reference).
			 */
			do_action_ref_array( 'loop_start', array( &$this ) );

		$post = $this->next_post();
		$this->setup_postdata( $post );
	}

	/**
	 * Determines whether there are more posts available in the loop.
	 *
	 * Calls the {@see 'loop_end'} action when the loop is complete.
	 *
	 * @since 1.5.0
	 *
	 * @return bool True if posts are available, false if end of loop.
	 */
	public function have_posts() {
...