我编写了一段简单的代码（从网上的各种教程中拼凑而成），它创建了一个简单的元框（称为“副标题”），并从管理区域中删除了自定义字段。

在我将代码放入类之前，一切都很好。一旦我这样做，元框就会停止保存到数据库。我怀疑这是因为我需要为构造函数定义一些参数，但我尝试的任何操作都会失败。我不知道出了什么问题，所以非常感谢您的帮助！代码如下：

class MySubBoxClass 
{  
    function __construct()
    {
        add_action( \'add_meta_boxes\', array( $this, \'meta_box_add\' ) );      //Hooks meta_box_add() onto the add_meta_boxes hook                                                                
        add_action( \'save_post\', array( $this, \'save_meta_box\', 10, 2 ) );   //Hooks save_meta_box() onto the save_post hook                                                                          
        add_action(\'admin_init\', array( $this, \'remove_custom_meta_boxes\') );//Hooks remove_custom_meta_boxes() onto admin_init  
    }

    public function meta_box_add()    //Function that triggers the add_meta_box() Wordpress function 
    {
        add_meta_box( \'meta-box-id\', \'SUBHEADING\', array($this, \'html_form_func\'), \'post\', \'normal\', \'high\' );  
        //Adds meta box with HTML id "meta-box" to the admin panel in the edit posts screen  
        //Calls the add_meta_box_cb_function() which creates the HTML form (see below)  
    }


    public function html_form_func( $object ) //Creates the HTML form and outputs its value if it has one   
    {  
        wp_nonce_field( basename( __FILE__ ), \'meta_box_nonce\' );

        <label><input type="text" name="subheading" id="meta-box-input" size="144" value="<?php echo get_post_meta( $object->ID, \'subheading\', true ); ?>" /></label>        
    }

    public function save_meta_box( $post_id, $post ) 
    {
        //Verifies the nonce before proceeding.
        if ( !isset( $_POST[\'meta_box_nonce\'] ) || !wp_verify_nonce( $_POST[\'meta_box_nonce\'], basename( __FILE__ ) ) )
            return $post_id;

        //Gets the post type object
        $post_type = get_post_type_object( $post->post_type );


        //Assigns \'$new_meta_value\' variable the value that was newly submitted through the HTML form input named \'subheading\' 
        $new_meta_value = ( isset( $_POST[\'subheading\'] ) ? esc_attr( $_POST[\'subheading\'] ) : \'\' );

        //Assigns\'$meta_key\' variable the value \'subheading\'  
        $meta_key = \'subheading\';

        //Assigns $meta_value variable the value of the custom field (identified by the key \'$meta_key\') that is currently 
        //associated with that post 
        $meta_value = get_post_meta( $post_id, $meta_key, true );

        //If a new meta value was added and the previous meta value had no value (== \'\'), add the new meta value
        if ( $new_meta_value && $meta_value == \'\' )
            add_post_meta( $post_id, $meta_key, $new_meta_value, true );

        //If the new meta value does not match the old value, update it
        elseif ( $new_meta_value && $new_meta_value != $meta_value )
            update_post_meta( $post_id, $meta_key, $new_meta_value );

        //If there is no new meta value but an old value exists, delete it
        //elseif ( $new_meta_value == \'\' && $meta_value )
        //delete_post_meta( $post_id, $meta_key, $meta_value );
    }

    public function remove_custom_meta_boxes() 
    {
        remove_meta_box(\'postcustom\',\'post\',\'normal\');
        remove_meta_box(\'postcustom\',\'page\',\'normal\');
    }
}

$MySubBoxClass = new MySubBoxClass;