autolisp

name	autolisp
description	Write, review, debug, and validate AutoLISP or DCL for AutoCAD-MCP using the shipped guidance and autolisp-validate development tool.

AutoLISP Skill

Use this skill when a task requires AutoLISP or DCL source. Use autocad-mcp for shipped read, write, and plot operations. Handwritten AutoLISP is appropriate when the requested behavior is outside that public tool surface. Do not replace a shipped autocad-mcp operation with hand-written AutoLISP during normal drawing work.

Working sequence

1. Read the target project's loader, command entry points, and existing naming conventions.

2. State the intended host: full AutoCAD, an AutoCAD console process, or a source-only validation environment.

3. List every drawing mutation, system variable, external file, and non-built-in function the routine will use.

4. Keep the worker independent of prompts where practical. Add a c: wrapper only when interactive input is required.

5. Localize temporary bindings after / in each defun.

6. Restore changed state and close any undo boundary on success, cancellation, and error paths.

7. Validate every changed .lsp file and inspect warnings in the context of the real input range:

   autolisp-validate path/to/file.lsp
   

   From this repository, the equivalent development command is cargo run -p autolisp-validate -- path/to/file.lsp.

The validator reports parenthesis errors and a deliberately small set of AutoLISP-specific convention hazards. A clean result is not execution evidence; run host-dependent code in the exact supported AutoCAD environment.

Choosing an API

• Use the entity functions for current-drawing records when their contract covers the operation.
• In full AutoCAD on Windows, ActiveX may be appropriate after explicit (vl-load-com) initialization.
• Do not assume an interactive application object, dialog, editor selection, or prompt is available in a console process.
• Keep launch, file-opening, save, and exit behavior outside the drawing worker so they can be verified separately.

See references/06_execution_contexts_and_headless.md before writing code that must run without the full UI.

Command shape

A command should make ownership of state visible. This small shape is a review aid, not a drop-in implementation:

(defun c:ACMCP_SAMPLE (/ *error* previous_echo)
  (setq previous_echo (getvar "CMDECHO"))

  (defun *error* (message)
    (if previous_echo
      (setvar "CMDECHO" previous_echo))
    (if (and message
             (not (wcmatch (strcase message) "*CANCEL*,*QUIT*,*EXIT*")))
      (prompt (strcat "\nACMCP_SAMPLE failed: " message)))
    (princ))

  (setvar "CMDECHO" 0)
  ;; Call a separately tested worker here.
  (setvar "CMDECHO" previous_echo)
  (princ))

Adapt the cleanup to the resources the real routine acquires. If the command starts an undo group, opens a file, loads a dialog, or creates a COM object, its cleanup path must own that resource explicitly.

DCL boundary

For a DCL dialog:

• give each interactive tile a unique key;
• resolve the DCL file path rather than relying on an undeclared support path;
• reject a failed load_dialog or new_dialog;
• set initial state and callbacks before entering the dialog loop;
• copy accepted values out before applying drawing changes; and
• unload every successfully loaded dialog.

Read references/05_dcl_dialogs.md and references/dcl/reference-dcl-summary.md for the maintained subset. Consult the current Autodesk reference for attributes or platform support not documented there.

Reference routing

Need	File
Command structure and cleanup	references/01_core_playbook.md
Entities and selection sets	references/02_entity_and_selection_cookbook.md
Validator-backed failure patterns	references/03_pitfalls_and_failure_modes.md
Persistent drawing records	references/04_object_model_and_internals.md
DCL integration	references/05_dcl_dialogs.md
GUI and console boundaries	references/06_execution_contexts_and_headless.md
DCL names used by this skill	references/dcl/reference-dcl-summary.md
Source and rights record	references/README.md and references/documentation-provenance.json