C++: A Dialog Programming with the C++ Standard Library

Review

We started this chapter with the DatedStockItem class from Chapter 9, which extended the StockItem class by adding an expiration date field to the member variables that DatedStockItem inherited from the StockItem class. While this was a solution to the problem of creating a class based on the StockItem class without having to rewrite all the functioning code in the latter class, it didn't solve the bigger problem: how to create a Vec of objects that might or might not have expiration dates. That is, we wanted to be able to mix StockItem objects with DatedStockItem objects in the same Vec, which can't be done directly in C++.

Part of this difficulty was solved easily enough by making a Vec of StockItem*s (i.e., pointers to StockItems), ...