Figure 1: The universal method window. When you double click on the recursive factorial method, the icon zooms out to become the first window seen in figure 2. The name of the method is shown as the window title. The icon next to the window title signifies that the window contains a method diagram. The bars at the top and bottom of the window content represent the input data and output data to the method. Data flows from the input bar to the output bar along links represented by lines. The data lines have a root at the upper end into which the data flows and a terminal at the lower end out of which the data flows. Both roots and terminals are represented by circles. In general, there will be as many roots on the input bar as there is data available. There will also be as
many terminals on the output bar as there are results to be passed on.
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Figure 2: The recursive factorial method.
Notice that the input root is connected to three other icons. The icons represent operations that will act on the data. There are two kinds of operations: primitives or methods. Primitives are operations such as “≤” and “*” that are built into Prograph for your use. Many of the common operations that you would want to perform are included. If you need a primitive that isn’t available, Prograph allows you to link in code from MPW or Lightspeed C. Methods are operations you create within Prograph and come in two varieties - class and universal. Class methods belong to the class in which they are defined and are created to