Object Oriented PHP, array is null when returned from method

Question

Trying to grok object-oriented PHP. I have a recursive method to return comments and their replies and compile them to a flat array $comments_list .

<?php

class RedditPosts
{
    public function get_post_ids($from, $limit)
    {
        // GET POSTS
        $list = json_decode(file_get_contents("http://www.reddit.com/$from.json?limit=$limit"));
        sleep(2); //after every page request

        $post_ids = array();
        foreach($list->data->children as $post) {
            $post_ids[] = $post->data->id;
        }
        return $post_ids;
    }
}

class RedditComments
{
    static $comments_list = array();

    public function get_comments($post_id)
    {
        $comments_object = json_decode(file_get_contents("http://www.reddit.com/comments/$post_id.json"));
        sleep(2);

        $top_comments = $comments_object[1]->data->children;
        //var_dump($top_comments);
        self::get_sub_comments($top_comments);
    }

    static function get_sub_comments($root_comments)
    {
        foreach($root_comments as $comment)
        {
            self::$comments_list[] = $comment;
            //echo $comment->data->body . "<br/>"

            if ($comment->data->replies != '')
            {
                self::get_sub_comments($comment->data->replies->data->children);
            }
        }
        var_dump(self::$comments_list);
        return self::$comments_list;

    }
}

/******************************MAIN************************************/

$ps = new RedditPosts();
$my_posts = $ps->get_post_ids("r/learnprogramming", 2);

$cm = new RedditComments();
$my_comments = $cm->get_comments($my_posts[0]);
var_dump($my_comments);

?>

I do a var_dump right before returning it and it is filled and looks correct but when I call it outside the method it is null. Probably an issue with scope but I'm new at this and cant figure out where and I've hit a wall. Help appreciated!

Answer 1

You don't return anything from get_post_ids . self::get_sub_comments($top_comments); should be self::get_sub_comments($top_comments); ?