代码在 php 7 中运行良好，但在 php 8 中返回错误

Question

i have the code bellow that runs fine in php 7. But when i change php to version 8 it gives me an error

The code

class WC_plugin {
        
    public static function init() {
        global $wp_filter;
        global $post;
        global $wpdb;
        add_action( 'woocommerce_update_product', __CLASS__ . '::createXml' );
    }
    
    
    function createXml($product_id){
        // Do something
        

    }
    
}

WC_plugin::init();

And the error i am getting is the bellow one

Argument #1 ($callback) must be a valid callback, non-static method WC_plugin::createXml() cannot be called statically

Can anyone help with the above?

Answer 1

The problem seems to be clearly defined:

Argument #1 ($callback) must be a valid callback, non-static method WC_plugin::createXml() cannot be called statically

You can't call a method statically (with :: ) if this method is not static...

createXml() method is not a static method so you can't call it like this in your add_action: WC_plugin::createXml();

Maybe this should work better

add_action( 'woocommerce_update_product', [ $this ,'createXml' ] );

Which corresponds to the following call WC_plugin->createXml();

I hope this answer will be useful to you.