WPに任意のURLを追加するためのクラス

class-addrewriterules.php

<?php

if (!class_exists('WP_AddRewriteRules')):
class WP_AddRewriteRules{
    private $rule     = null;
    private $query    = null;
    private $callback = null;

    function __construct($rule, $query, $callback)
    {
        $this->rule     = $rule;
        $this->query    = $query;
        $this->callback = $callback;
        add_filter('query_vars', array(&$this, 'query_vars'));
        add_action(
            'generate_rewrite_rules',
            array(&$this, 'generate_rewrite_rules')
        );
        add_action('wp', array(&$this, 'wp'));
    }

    public function generate_rewrite_rules($wp_rewrite)
    {
        $new_rules[$this->rule] = $wp_rewrite->index . '?' . (
            strpos($this->query, '=') === FALSE
            ? $this->query . '=1'
            : $this->query
        );
        $wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
    }

    private function parse_query($query)
    {
        $query = explode('&', $query);
        $query = explode(
            '=',
            is_array($query) && isset($query[0]) ? $query[0] : $query
        );
        return (is_array($query) && isset($query[0]) ? $query[0] : $query);
    }

    public function query_vars($vars)
    {
        $vars[] = $this->parse_query($this->query);
        return $vars;
    }

    public function wp()
    {
        if (get_query_var($this->parse_query($this->query))) {
            call_user_func($this->callback);
        }
    }
}
endif;

// eol

example.php

<?php

// 例

// プラグイン有効化時にリライトルールをクリアする。
register_activation_hook(__FILE__, 'flush_rewrite_rules');

new WP_AddRewriteRules(
    'mystyle.css$',
    'mystyle',
    'callback_function'
);

// 指定されたURLでアクセスがあった際に実行されるコールバック
function callback_function()
{
  header('Content-type: text/css; charset=UTF-8');
  echo 'body {background-color: #ff0000}';
  exit; // exitがないと続けてwp本体の処理が行われてしまう。
}

別プラグインでこのやり方にツッコミが入ったけど意味がわかりませぬ。

the rewrite flush happens BEFORE init, which is a big no-no according to the WordPress Codex. By flushing the rewrites before init, the rewrites for custom post types are not being generated and permalinks to these pages are broken. In a normal configuration the problem can be easily solved by going to the Permalinks page of the settings and by clicking on update.

コンストラクタでflushを登録せずにAddRewriteRules->flush()みたいなメソッドを用意するだけにしよう。