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

Avoiding an Infinite Regress During Construction

We can't do that because the default constructor for StockItem calls the default constructor for UndatedStockItem; that is, the function that we're examining right now. Therefore, if we allow the StockItem default constructor to initialize the StockItem part of an UndatedStockItem, that default constructor will call our UndatedStockItem default constructor again, which will call the StockItem default constructor again, and the program will eventually use up all the stack space and die.

To avoid this problem, we have to make a special constructor for StockItem that doesn't create an UndatedStockItem object and therefore avoids an indefinitely long chain of constructor calls. As no one outside the ...