BUILT-IN WOLFRAM LANGUAGE SYMBOL
initiates a dialog for every expression used in the evaluation of expr.
initiates a dialog only for expressions which match form.
initiates dialogs only for expressions whose evaluations use transformation rules associated with the symbol s.
- The expression to be evaluated when a dialog is called is given as Out[$Line] of the dialog, wrapped in HoldForm. The expression can be seen by asking for when the dialog is first started.
- Any value returned from the dialog is discarded.
- TraceDialog[expr] returns the result of evaluating expr.
Trace evaluation of an expression, entering a Dialog whenever addition is encountered:
In the dialog you can look at the evaluation stack:
This returns from the first dialog:
Another dialog has started:
In the dialog, you can check evaluations to see if they come out as you expect:
Return from the second dialog. Since there are no more additions, the evaluation will finish: