Stepping through the Debugging Example

First, load the yinyang.lsp file and run the yinyang function to see what it does. The function draws the yin-yang symbol, which is used in many religions:

When you run the program, VLISP passes control to AutoCAD and you need to respond to the prompts in the AutoCAD Command window.

VLISP evaluates AutoLISP programs by evaluating the expressions contained in parentheses. These parenthetical expressions are similar to operators in other programming languages such as C++ and Visual Basic 6. The VLISP debugger uses an expression-based approach, unlike the line-by-line debuggers of languages such as C. In the expression-based approach, the debugger can suspend program execution immediately before or after the evaluation of any expression.

Debugging options are controlled from several different places within VLISP, including the text editor, the System Console, and various menus.