## Expression Builder

The Expression Builder guides the user through the construction of Expressions, which are the cornerstones of the Table Generator, using series of dialog boxes. The Expression Builder is activated from the Build Expression item of the Expressions sub-menu of the Functions menu of the Node Table.

The Expression Builder assists the user in building expressions by providing a simple user interface for selecting a function or an operator and specifying its arguments. When selected, the Build Expression item causes a dialog window to appear, which shows the functions available (the actual set of functions depends on the type of the node associated with the current node table). An example is shown in Figure 1. The functions are organized in a number of categories to make it faster to find a particular function.

Figure 1: The Select Function dialog of the Expression Builder.

After the user has selected a function, the Specify Arguments dialog of the Expression Builder appears. This dialog prompts the user for arguments to the selected function. Figure 2 shows the Specify Arguments dialog for the + operator.

Each argument is itself an expression and can therefore be built using the Expression Builder. Pressing the Select button next to the argument text field will start the Expression Builder for that argument.

If you want to use a parent in an expression, you must use its unique name. You can select a parent in the Parents list and then press the Insert button to insert it into the argument you are currently editing. Only discrete chance nodes and decision nodes can appear in expressions.

Figure 2: The Specify Arguments dialog of the Expression Builder.

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