752: Mainline

Now that you know how to produce simple displays, such as the one in Segment 749, you can create more elaborate displays, such as the display shown in Segment 668.

The principal differences between the simple meter defined in Segment 748 and the complex meter defined in AppendixB are:

• The complex meter has a nice look, that you produce by using a little trigonometry to draw a professional-looking dial.
• The complex meter's setters limit the value shown by the pointer to the minimum and maximum values allowed.

On the other hand, the meter defined in Segment 748 and the meter defined in AppendixB both implement the same interface, MeterInterface, defined in Segment 714. Accordingly, you can readily substitute the more elaborate meter for the simple meter in any program that expects the Meter class to implement MeterInterface.