Design Patterns Explained: A New Perspective on Object-Oriented Design

Understand the Vocabulary

The first task in analysis is to understand the vocabulary used by the users and the experts in the problem domain. The most important terms used are those that describe the dimensions and geometry in the sheet metal.

As shown in Figure 3-1, a piece of sheet metal is cut to a particular size and has shapes cut out inside it. Experts call these cutouts by the general name “feature.” A piece of sheet metal can be fully specified by its external dimensions and the features contained in it.

The types of shapes—features—that may be found in a piece of sheet metal are described in Table 3-1. These are the shapes the system will have to address.

Table 3-1. Shapes Found in a Piece of Sheet Metal

Shape	Description
Slot	Straight ...