全局变量不选择子函数值

Question

我使用了函数$extra_charges和woo_add_extra_fee()中使用的变量wl8OrderPlacedTriggerSomething()。由于某种原因，它总是打印为零（即使在满足if条件后）。

<?php
    $extra_charges=0;

    public function woo_add_extra_fee() {
        global $woocommerce;
        $available_gateways = WC()->payment_gateways->get_available_payment_gateways();
        $current_gateway = WC()->session->chosen_payment_method;
        if($current_gateway=='cod'){
            global $extra_charges;
            $current_gateways_detail = $available_gateways[$current_gateway];

            $disable_cod_adv = $current_gateways_detail->settings['disable_cod_adv'];
            if($disable_cod_adv && $disable_cod_adv=='yes'){return $totals;}

            $current_gateway_id = $current_gateways_detail->id;
            $current_gateway_title = $current_gateways_detail->title;
            $extra_charges_id = 'woocommerce_'.$current_gateway_id.'_extra_charges';
            $extra_charges_type = $extra_charges_id.'_type';
            $extra_charge_min_amount = (float)$current_gateways_detail->settings['extra_charge_min_amount'];
            $extra_charges = (float)$current_gateways_detail->settings['extra_charges'];
            $extra_charges_type = $current_gateways_detail->settings['extra_charges_type'];
            $roundup_type = $current_gateways_detail->settings['roundup_type'];
            $extra_charges_msg = $current_gateways_detail->settings['extra_charges_msg'];
            if(!$extra_charges_msg){$extra_charges_msg = 'COD Charges';}

            //get cart total
            $total = $woocommerce->cart->subtotal;

            if($extra_charges){
                if($extra_charges_type=="percentage"){
                    $total = $total + round(($total*$extra_charges)/100,2);
                }else{
                    $total = $total + $extra_charges;
                }
                if($roundup_type>0)
                {
                    $extra_add = $roundup_type -($total%$roundup_type);
                    $total = $total+$extra_add;
                    $extra_charges = $extra_charges+$extra_add;

                }

                //$this->current_extra_charge_min_amount = $extra_charge_min_amount;
                //$this->current_gateway_title = $current_gateway_title;
                //$this->current_gateway_extra_charges = $extra_charges;
                //$this->current_gateway_extra_charges_type_value = $extra_charges_type;
                $extra_fee_option_taxable = 0;
                //if cart total less or equal than $min_order, add extra fee
                //$extra_fee_option_label = sprintf(__('%s Extra Charges <small>for purchase less than %s</small>','askoracle'),$this->current_gateway_title,woocommerce_price($this->current_extra_charge_min_amount));
                $extra_fee_option_label = $extra_charges_msg;
                //$extra_fee_option_label = get_woocommerce_currency();
                $extra_charges = 0;
                if (get_woocommerce_currency() == "SAR")
                    $extra_charges = 20;
                if (get_woocommerce_currency() == "QAR")
                    $extra_charges = 20;
                if (get_woocommerce_currency() == "AED")
                    $extra_charges = 0;
                if (get_woocommerce_currency() == "EGP")
                    $extra_charges = 90;
                if (get_woocommerce_currency() == "JOD")
                    $extra_charges = 4;
                if (get_woocommerce_currency() == "BHD")
                    $extra_charges = 2;
                if (get_woocommerce_currency() == "KWD")
                    $extra_charges = 2;
                if (get_woocommerce_currency() == "OMR")
                    $extra_charges = 2;
                if (get_woocommerce_currency() == "LBP")
                    $extra_charges = 7500;
                if($extra_charge_min_amount>=$total || empty($extra_charge_min_amount)){
                    $woocommerce->cart->add_fee($extra_fee_option_label, $extra_charges, $extra_fee_option_taxable );
                }
            }
        }

    }

}




$hook_to = 'woocommerce_thankyou';
$what_to_hook = 'wl8OrderPlacedTriggerSomething';
$prioriy = 111;
$num_of_arg = 1;    
add_action($hook_to, $what_to_hook, $prioriy, $num_of_arg);

function wl8OrderPlacedTriggerSomething($order_id){
      global $extra_charges;
      //do something...
      update_post_meta( $order_id, "cod_fee", $extra_charges);
}