Nonvirtual Calls Are Resolved at Compile Time【c++ primer】

Regardless of the actual type of the argument passed to print_total , the call of book is resolved at

compile time to Item_base::book .

Even if Bulk_item defined its own version of the book function, this call

would call the one from the base class.

Nonvirtual functions are always resolved at compile time based on the type of the object, reference, or pointer from which the function is called. The type of item is reference to const Item_base , so a call to a nonvirtual function on that object will call the one from Item_base regardless of the type of the actual object to which item refers at run time.