setup_postdata()　WordPress関数

<?php

//wp-includes/query.phpより

/**
 * Set up global post data.
 *
 * @since 1.5.0
 * @since 4.4.0 Added the ability to pass a post ID to `$post`.
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
 * @return bool True when finished.
 */
function setup_postdata( $post ) {
	global $wp_query;

	if ( ! empty( $wp_query ) && $wp_query instanceof WP_Query ) {
		return $wp_query->setup_postdata( $post );
	}

	return false;
}

//class-wp-query.phpより
/**
	 * Set up global post data.
	 *
	 * @since 4.1.0
	 * @since 4.4.0 Added the ability to pass a post ID to `$post`.
	 *
	 * @global int     $id
	 * @global WP_User $authordata
	 * @global string  $currentday
	 * @global string  $currentmonth
	 * @global int     $page
	 * @global array   $pages
	 * @global int     $multipage
	 * @global int     $more
	 * @global int     $numpages
	 *
	 * @param WP_Post|object|int $post WP_Post instance or Post ID/object.
	 * @return true True when finished.
	 */
	public function setup_postdata( $post ) {
		global $id, $authordata, $currentday, $currentmonth, $page, $pages, $multipage, $more, $numpages;

		if ( ! ( $post instanceof WP_Post ) ) {
			$post = get_post( $post );
		}

		if ( ! $post ) {
			return;
		}

		$elements = $this->generate_postdata( $post );
		if ( false === $elements ) {
			return;
		}

		$id           = $elements['id'];
		$authordata   = $elements['authordata'];
		$currentday   = $elements['currentday'];
		$currentmonth = $elements['currentmonth'];
		$page         = $elements['page'];
		$pages        = $elements['pages'];
		$multipage    = $elements['multipage'];
		$more         = $elements['more'];
		$numpages     = $elements['numpages'];

		/**
		 * Fires once the post data has been setup.
		 *
		 * @since 2.8.0
		 * @since 4.1.0 Introduced `$this` parameter.
		 *
		 * @param WP_Post  $post The Post object (passed by reference).
		 * @param WP_Query $this The current Query object (passed by reference).
		 */
		do_action_ref_array( 'the_post', array( &$post, &$this ) );

		return true;
	}