全球的rewind_posts

File: wp-includes/query.php
784: /**
785:  * Rewind the loop posts.
786:  *
787:  * @since 1.5.0
788:  *
789:  * @global WP_Query $wp_query Global WP_Query instance.
790:  */
791: function rewind_posts() {
792:    global $wp_query;
793:    $wp_query->rewind_posts();
794: }

以及rewind_posts 从…起WP_Query 班

File: wp-includes/class-wp-query.php
3144:    * Rewind the posts and reset post index.
3145:    *
3146:    * @since 1.5.0
3147:    * @access public
3148:    */
3149:   public function rewind_posts() {
3150:       $this->current_post = -1;
3151:       if ( $this->post_count > 0 ) {
3152:           $this->post = $this->posts[0];
3153:       }
3154:   }

可以帮助我们了解$wp_query 使用全局rewind_posts.

---

codex 您设置的指针：

// main loop
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<?php the_content(); ?>
<?php endwhile; endif; ?>

// rewind
<?php rewind_posts(); ?>

// new loop
<?php while (have_posts()) : the_post(); ?>
<?php the_content(); ?>
<?php endwhile; ?>

表明这与$the_post 方法

那么，什么是the_post()?

File: /class-wp-query.php
3095:   public function the_post() {
3096:       global $post;
3097:       $this->in_the_loop = true;
3098: 
3099:       if ( $this->current_post == -1 ) // loop has just started
3100:           /**
3101:            * Fires once the loop is started.
3102:            *
3103:            * @since 2.0.0
3104:            *
3105:            * @param WP_Query &$this The WP_Query instance (passed by reference).
3106:            */
3107:           do_action_ref_array( \'loop_start\', array( &$this ) );
3108: 
3109:       $post = $this->next_post();
3110:       $this->setup_postdata( $post );
3111:   }

至少我们可以理解global $post 每次迭代while 环

理解的关键是next_post() 方法

File: wp-includes/class-wp-query.php
3068:   /**
3069:    * Set up the next post and iterate current post index.
3070:    *
3071:    * @since 1.5.0
3072:    * @access public
3073:    *
3074:    * @return WP_Post Next post.
3075:    */
3076:   public function next_post() {
3077: 
3078:       $this->current_post++;
3079: 
3080:       $this->post = $this->posts[$this->current_post];
3081:       return $this->post;
3082:   }

该方法最终解释了我们增加当前post指针的原因：

$this->current_post++;

请注意，在整个变量上方的表达式中$this->current_post 将递增。

($this->current_post)++;

这相当于：

$this->current_post = $this->current_post + 1;

对于那些讨厌承认语法的人$this->current_post++; 增加变量非常酷。

回顾一下：

自从我们打电话以来the_post() 并增加了$this->current_post 指针如果我们计划再次循环，现在需要将该指针设置为-1。

3149:   public function rewind_posts() {
3150:       $this->current_post = -1;
3151:       if ( $this->post_count > 0 ) {
3152:           $this->post = $this->posts[0];
3153:       }
3154:   }

虽然很奇怪，但它确实有效。