Lesson 5.16 – Using the Visual LISP Editor

🧠 Lesson 5.16 – Using the Visual LISP Editor (VLIDE)

Learn how to write, debug, and manage your AutoLISP code in AutoCAD’s built-in development environment, the Visual LISP Editor.

📚 What You’ll Learn

By the end of this lesson, you’ll be able to:

Open and navigate the Visual LISP Editor (VLIDE)
Write and format structured AutoLISP code
Set breakpoints and step through your code
Use debugging tools to find and fix issues

🧠 Why It Matters

The Visual LISP Editor (VLIDE) is your development workshop. It provides syntax highlighting, real-time debugging, and tools for writing efficient, error-free code. If you’re serious about AutoLISP, mastering VLIDE is essential.

🛠️ Tools You’ll Use

Tool / Feature	Purpose
VLIDE (`VLISP` command)	Launches the Visual LISP Editor
Debug Toolbar	Step through functions and inspect variables
Watch & Breakpoints	Monitor expressions and control execution flow
Format Code Tool	Auto-formats your code for clarity

🧭 Lesson Structure

1️⃣ Launching the Visual LISP Editor

To open VLIDE:

In AutoCAD, type VLISP or VLIDE at the command line
The Visual LISP Editor window will open
Use File → New File to start a new .lsp script
Use File → Open File to edit an existing .lsp

2️⃣ Writing and Formatting Code

Use the editor to write clean, readable LISP code:

(defun c:greet ( / )
  (alert "Hello from VLIDE!")
  (princ)
)

📝 To auto-format:

Highlight code → Right-click → Format Selection
Or: Tools → Format Code

3️⃣ Using Breakpoints

Breakpoints let you pause execution:

Click in the left margin next to a line of code
A red dot indicates the breakpoint
Run the routine; VLIDE will pause at the breakpoint

Use Debug → Run or Step Into (F8) to continue execution step-by-step.

4️⃣ Watching Variables

You can monitor variable values during execution:

Right-click a variable → Add Watch
Open Tools → Watch Window to view values
Update expressions to track changes as code runs

🧠 Tip: Use (print var) in the command line to debug simple issues quickly.

5️⃣ Using the Console and Trace Tools

Console allows for testing code snippets live
Use (trace) and (untrace) to monitor function calls
Useful for identifying logic errors in complex routines

✅ Lesson Checklist

Task	Completed
Opened VLIDE from AutoCAD	☐
Wrote and formatted a simple LISP function	☐
Set at least one breakpoint	☐
Stepped through code with the debugger	☐
Watched a variable in real-time	☐

📌 Quick Tips

Tip	Why It Helps
Use descriptive names and section comments	Easier to debug and maintain
Format regularly	Keeps code legible and clean
Use `(princ)` in your functions	Prevents command-line clutter
Backup before debugging	Avoids overwriting working code

🧩 Real-World Applications

Use Case	How VLIDE Helps
Debugging attribute fill issues	Step through insertion and data writing logic
Writing reusable math tools	Watch variables in loops or calculations
Teaching new users	Live demo with breakpoints and console output

📁 Files and Resources

File / Resource	Description
`vlide_shortcuts_cheatsheet.docx`	Common keyboard shortcuts and actions in VLIDE
`debug_walkthrough_sample.lsp`	Script with a built-in bug for step-by-step practice
`vlide_checklist.docx`	Step-by-step debugging checklist

📖 Review Table

Feature	Description	How to Access
Breakpoints	Pause code execution at a specific line	Click margin beside code line
Watch window	Observe variable changes	Tools → Watch Window
Step Into (F8)	Executes code line-by-line	Debug Toolbar or `F8` key
Format Code	Auto-indents code	Tools → Format Code or right-click selection