.
.
.
int a = 5;
MacroResolver.OnResolveCustomMacro += MacroResolver_OnResolveCustomMacro;

private void MacroResolver_OnResolveCustomMacro(object sender, MacroEventArgs e)
{
.
.
.
}

        protected override string GetInvoiceInternal(int orderId)
        {
            int currency = 0;
            int currency_ID = 0;
            OrderInfo oi = OrderInfoProvider.GetOrderInfo(orderId);
            if (oi != null)
                currency = oi.OrderCurrencyID;
            if (currency != 0)
            {
                CurrencyInfo ci = CurrencyInfoProvider.GetCurrencyInfo(currency);
                if (ci != null)
                    currency_ID = ci.CurrencyID;
            }
            
            MacroResolver.OnResolveCustomMacro += MacroResolver_OnResolveCustomMacro;
            MacroResolver.OnResolveCustomMacro += (o, e) => { e.currency_ID = currency_ID; MacroResolver_OnResolveCustomMacro(o, e); };
            return oi.OrderInvoice;
        }
        
        private void MacroResolver_OnResolveCustomMacro(object sender, MacroEventArgs e)
        {
            switch (e.Expression)
            {
                case "currency.currencyID":
                    e.Match = true;
                    e.Result = currency_ID;
                    break;
            }
        }