Debugging is usually the most time-consuming stage in the development of any program. For this reason, VLISP includes a powerful debugger that provides the following features:

• Tracing of program execution
• Tracing of variable values during program execution
• Viewing the sequence in which various expressions are evaluated
• Inspecting the values of parameters used within function calls
• Interrupting program execution
• Stepping through program execution one instruction at a time
• Inspecting the stack

VLISP provides the following facilities to implement these features:

Break Loop Mode

Halts program execution at specified points, allowing you to look at and modify the value of objects during the break. Examples of AutoLISP^® objects are variables, symbols, functions, and expressions.

Inspect

Provides detailed information on an object in an Inspect dialog box. If the object being inspected is composed of nested objects (a list, for example), the Inspect feature allows you to inspect all the components, each one listed on its own line within the window. You can also recursively inspect any nested object until an atomic object (such as a number or a symbol) is reached.

Watch Window

Watches the values of variables during program execution. The content of the Watch window is updated automatically. This means that if the value of a variable placed in the Watch window is changed, this change will automatically be reflected in the Watch window.

Trace Stack Facility

Views the function call stack. The call stack is a mechanism by which VLISP records the sequence of functions as they are executed by your program. You can view the stack during a debugging session (when the program is in a suspended state, such as stepping through after a breakpoint), or after your program has crashed. If viewed after your program crashes, the function call stack shows what VLISP was doing at the moment the application failed.

Trace Facility

A standard LISP facility, logs the calls and returns values of traced functions into the special Trace window.