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(defun c:EraseObjects ()
(setq ss (ssget))
(command "_.ERASE" ss "")
(princ)
)Coding works best on desktop or with an external keyboard.
Erase Selected Objects - Autolisp Typing CST Test
Erase Selected Objects — Autolisp Code
Deletes selected objects from the drawing.
(defun c:EraseObjects ()
(setq ss (ssget))
(command "_.ERASE" ss "")
(princ)
)Autolisp Language Guide
AutoLISP is a dialect of the Lisp programming language built specifically for automating tasks, customizing workflows, and extending functionality within Autodesk AutoCAD software, enabling rapid development of scripts and commands to enhance CAD productivity.
Primary Use Cases
- ▸Automating drawing modifications
- ▸Custom command creation
- ▸Batch plotting and file management
- ▸Parametric drawing generation
- ▸Data extraction and CAD reporting
Notable Features
- ▸Embedded in AutoCAD environment
- ▸Dynamic interaction with drawing entities
- ▸Supports creation of custom commands
- ▸Integrated Visual LISP IDE for development
- ▸Ability to interface with external files and databases
Origin & Creator
Developed by Autodesk Inc., USA, as an extension of the Lisp programming language for CAD automation.
Industrial Note
Commonly used in AEC (Architecture, Engineering, Construction), mechanical design, civil engineering workflows, and production drafting where repetitive AutoCAD operations need automation.
Quick Explain
- ▸AutoLISP is embedded within AutoCAD and allows scripting for automation of repetitive tasks.
- ▸Supports creating custom commands, functions, and routines to manipulate drawings.
- ▸Provides access to AutoCAD objects, layers, entities, and properties programmatically.
- ▸Often combined with Visual LISP IDE for debugging and code management.
- ▸Widely used in architecture, engineering, and manufacturing for CAD customization.
Core Features
- ▸Functions and macros for CAD tasks
- ▸Access to AutoCAD object model
- ▸Event handling via reactors
- ▸File I/O and system operations
- ▸Error handling and debugging tools
Learning Path
- ▸Learn AutoCAD basics
- ▸Understand AutoLISP syntax and data types
- ▸Write simple functions and commands
- ▸Practice entity manipulation and selection sets
- ▸Build complex automation scripts
Practical Examples
- ▸Automatically renumber drawing blocks
- ▸Batch layer visibility toggle
- ▸Parametric stair or furniture generation
- ▸Extract coordinates of selected entities to CSV
- ▸Generate drawing sheets from templates
Comparisons
- ▸AutoLISP vs VBA: AutoLISP more CAD-centric, VBA more general-purpose
- ▸AutoLISP vs .NET API: .NET provides modern language support, AutoLISP is simpler for legacy CAD scripts
- ▸AutoLISP vs Python (PyAutoCAD): Python allows external automation, AutoLISP is native inside AutoCAD
- ▸AutoLISP vs ScriptPro: ScriptPro handles batch operations, AutoLISP scripts are customizable
- ▸AutoLISP vs Dynamo: Dynamo is visual and parametric, AutoLISP is code-based scripting
Strengths
- ▸Rapid automation of repetitive CAD tasks
- ▸No external compiler needed
- ▸Highly flexible scripting with Lisp logic
- ▸Direct access to drawing database
- ▸Strong integration with AutoCAD commands
Limitations
- ▸Only works within AutoCAD environment
- ▸Performance limited for extremely large drawings
- ▸Not suitable for real-time CAD applications
- ▸Visual customization is limited compared to .NET API
- ▸Older syntax may be less familiar to new developers
When NOT to Use
- ▸For non-AutoCAD applications
- ▸When modern .NET or Python API offers better integration
- ▸For real-time CAD simulations
- ▸If extensive GUI customization is required
- ▸For cloud or web-based CAD automation
Cheat Sheet
- ▸(defun c:CommandName () ... ) -> Define command
- ▸(setq var value) -> Assign variable
- ▸(entget entity) -> Access entity data
- ▸(entmod entity) -> Modify entity
- ▸(command "LINE" pt1 pt2) -> Call AutoCAD command
FAQ
- ▸Can AutoLISP run outside AutoCAD? -> No, it requires AutoCAD.
- ▸Do I need to know Lisp? -> Basic understanding helps, AutoLISP is CAD-focused.
- ▸Can AutoLISP modify drawings programmatically? -> Yes, all supported entities.
- ▸Is AutoLISP still supported? -> Yes, in recent AutoCAD versions.
- ▸Can AutoLISP interact with external files? -> Yes, via file I/O commands.
30-Day Skill Plan
- ▸Week 1: Basic commands and functions
- ▸Week 2: Entity selection and modification
- ▸Week 3: Loops, conditionals, and recursion
- ▸Week 4: File I/O and batch processing
- ▸Week 5: Integration with external data and CAD workflows
Final Summary
- ▸AutoLISP is a CAD-focused scripting language embedded in AutoCAD.
- ▸Enables rapid automation of repetitive tasks and custom commands.
- ▸Strong access to AutoCAD entities, layers, and drawing database.
- ▸Supports integration with external files and batch processing.
- ▸Ideal for architects, engineers, and drafters automating workflows.
Project Structure
- ▸Main LISP script (.lsp)
- ▸Support function libraries
- ▸Configuration files or constants
- ▸Documentation and usage guide
- ▸Optional external data files (CSV, TXT)
Monetization
- ▸Custom AutoLISP development services
- ▸CAD workflow automation consulting
- ▸Batch processing solutions for engineering firms
- ▸Parametric drawing toolkits
- ▸Integration of CAD with external databases
Productivity Tips
- ▸Use modular functions for reuse
- ▸Test scripts on sample drawings first
- ▸Leverage selection sets for efficiency
- ▸Combine AutoLISP with DCL for user interaction
- ▸Keep script libraries organized and versioned
Basic Concepts
- ▸Atoms, lists, and symbols (Lisp data types)
- ▸Functions defined with (defun ...)
- ▸AutoCAD entities accessed via (entget) and (entmod)
- ▸Command creation using (defun c:CommandName ...)
- ▸Loops, conditionals, and recursion for automation