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Figure 16-5
Class Interface Diagram for ExtTime Class |
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subclass can be confusing because the prefix sub- usually implies something smaller than the original (for example, subset of a mathematical set). In contrast, a subclass is often bigger than its superclassthat is, it has more data and/or functions. |
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In Figure 16-5, you see an arrow between the two ovals labeled Increment. Because Time is a public base class of ExtTime, and because Increment is not overridden by ExtTime, the Increment function available to clients of ExtTime is the same as the one inherited from Time. We use the arrow between the corresponding ovals to indicate this fact. (Notice in the diagram that Time's constructors are operations on Time, not on ExtTime. The ExtTime class must have its own constructors.) |
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