July 2001
Beginner to intermediate
368 pages
6h 52m
English
book
Design Patterns Explained: A New Perspective on Object-Oriented Design
by Alan Shalloway, James R. Trott
Content preview from Design Patterns Explained: A New Perspective on Object-Oriented Design
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A Little More Detail
Figure 14-2 showed the basic structure of the case study. Figure 15-1 shows this structure in more detail. Here, I show that the SalesOrder object uses a SalesTicket object to print a sales ticket.
Figure 15-1. SalesOrder using SalesTicket.
As you saw in Chapter 14, SalesOrder uses a CalcTax object to calculate the tax on the order. To implement the printing function, SalesOrder calls the SalesTicket object, requesting that it print the ticket. This is a fine, reasonably modular design.
In the process of writing the application, suppose I get a new requirement to add header information to the SalesTicket.
How can I handle this ...