我正在构建许多自定义短代码，为了卸载大量可重用代码，我为所有要扩展的短代码类创建了一个抽象基类。

然而，当我试图引用$this 在add\\u shortcode（）函数中时，我收到以下错误：

Fatal error: Using $this when not in object context in...

然而，在add\\u shortcode（）函数之外（在其他类方法中），我的子类可以使用$this，可以预见地引用自身及其父类。

下面是我的子shortcode类和父抽象类的简化版本

父类

abstract class ABS_Shortcode {

    protected $order;

    public function __construct() {
        $this->order = \'\';
    }

    public function set_order_prop($value) {
        $this->order = $value;
    }

    public function get_order_prop() {
        return $this->order;
    }

    protected function setup_default_options() {
       //Setups up defaults not important for example. But does get called correctly from child class
    }
}

子类

class WC_Product_Categories extends ABS_Shortcode {

    protected $shortcode_base = \'wc_product_categories\';

    public function __construct() {
        parent::__construct();
        // Call to method in parent class works fine
        $this->setup_default_options();
        // Child method works fine
        $this->map_shortcode();
        // Have to use __CLASS__ instead of $this here to not throw an error. Not sure why
        add_shortcode( $this->shortcode_base, array( __CLASS__, "build_shortcode") );
    }
    protected function map_shortcode() {
        // Code to handle building shortcode attributes, not necessary for example
    }

    public function build_shortcode($atts, $content = null) {
        extract( shortcode_atts (
            // Setup defaults
            array(
                \'category\'                      => \'\',
                \'posts_per_page\'                => \'\',
                \'orderby\'                       => \'\',
                \'order\'                         => \'\',
                \'items_per_row\'                 => \'\',
                \'hide_empty\'                    => \'\',
            ), $atts) );

        //Call to parent class property or method throws error when using $this
        //Fatal error: Using $this when not in object context in...
        $this->order = \'ASC\';
        $this->set_order_prop(\'ASC\');

        //Call using parent:: works to call parent method. 
        //But inside parent class when using $this throws original error
        //Fatal error: Using $this when not in object context in...
        parent::set_order_prop(\'ASC\');

        // Try calling parent class property
        // Fatal error: Access to undeclared static property: ABS_VC_Shortcode::$order
        parent::$order;

    }
}
// Create class
$wc_categories = new WC_Product_Categories();

如果不从shortcode函数（build\\u shortcode）内部调用，所有这些错误都会消失。$这可以正确地引用子类或父类的属性和方法。

我想知道为什么在使用add\\u shortcode（）函数时，对$this的引用会引发错误。我怎么才能避开这个？

谢谢

array( __CLASS__, "build_shortcode")

array( "WC_Product_Categories", "build_shortcode")

WC_Product_Categories::build_shortcode();

array( $this, \'build_shortcode\' )

$this->build_shortcode();