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comp.cad.autocad AutoLISP FAQ (part 1/2) - general

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Posted-By: auto-faq
Archive-name: CAD/autolisp-faq/part1
Version: 2.28
Last-modified: 2002-06-25
Posted-By: Reini Urban <>
Posting-Frequency: monthly
Copyright: see Appendix [A]

See reader questions & answers on this topic! - Help others by sharing your knowledge
        Welcome to the comp.cad.autocad AutoLISP FAQ
          by Reini Urban <>

Autolisp is a scripting language for AutoCAD, a well known CAD package. 
This AutoLISP FAQ is posted to comp.cad.autocad, alt.cad.autocad and
the *.answers groups monthly. Some AutoCAD FAQ's are at but not posted to
comp.cad.autocad. The contents and the samples apply to all
releases of AutoLISP since Release 10, including Visual Lisp, Vital Lisp
and ACOMP. There's no special AutoLISP newsgroup.
Best are comp.cad.autocad and autodesk.autocad.customization,
but please don't bother comp.lang.lisp.
Source code of all functions in this FAQ is in FAQ-CODE.LSP
(for location see [A.1]), there's also a Winhelp file.
Thanks to all who have contributed. Corrections and contributions
always welcome. 
Please see

This is part 1/2 of the AutoLISP FAQ v2.28, which consists of:

    AutoLISP FAQ (part 1/2) - General
    AutoLISP FAQ (part 2/2) - Samples, code

| changes, + new in items from this version to the last posted version,
intermediate personal comments and uncertainties in <..>

  Table of Contents
  part 1:   General
     [0] The Future of AutoLISP? Should I learn it or VB instead?
       [0.1] What changed with AutoCAD 2000?
       [0.2] We cannot create ARX anymore?
     [1] Where can I find AutoLISP routines on the Internet?
       [1.1] Are the comp.cad.autocad articles stored somewhere?
       [1.2] Autodesk's SDK
     [2] What are the best books to learn AutoLISP?
       [2.1] Online AutoLISP documents, Winhelp [deleted]
       [2.2] AutoLISP Coding Style
     [3] How do I debug AutoLISP programs?
        [3.1] Native AutoLISP debuggers
        [3.2] Modular style, TRACE
        [3.3] BREAK function, debug-print
     [4] How can I protect my AutoLISP programs? Security
       [4.1] Kelvinate
       [4.2] Protect
       [4.3] Kelvinate and Protect
       [4.4] Convert
       [4.5] ACOMP
       [4.7] Lisp2C
       [4.6] Vital LISP Professional
       [4.8] Visual Lisp by Autodesk
     [5] AutoLISP compilers
       [5.1] ACOMP
       [5.2] Vital LISP Professional
       [5.3] Visual Lisp by Autodesk
       [5.4] Better ones: Common Lisp and Scheme
     [6] AutoLISP editors and other tools
       [6.1] AutoLISP editors
       [6.2] Analyzers, Packager and Parenthesis checkers
       [6.3] Pretty Printers
     [7] AutoLISP problems and bugs
     [8] Sorting with AutoLISP
     [9] Recursion
     [10] Iteration with MAPCAR,...
+    [11] S::STARTUP, My LISPs aren't loading at startup anymore
     [12] How to AUTOLOAD my programs?
     [13] How can I pass a variable number of
          arguments to a LISP function?
     [14] How can I avoid stack overflows?
     [15] (command "ROTATE3D") does not work! Why?
     [16] Lisp programs operating over multiple drawings
     [17] How to export Visual Lisp functions to AutoLISP/AutoCAD?
     [A] Disclaimer, Notes from the authors
       [A.1] FAQ Locations

  part 2:   Samples, code
     [20] General Helper functions
       [20.1] List manipulation
       [20.2] String manipulation
       [20.3] symbol->string
       [20.4] AutoCAD entity access
     [21] Sample Lisp programs
       [21.1] Globally change text, polylines, layer utils, date stamp
       [21.2] Plot dialog from within LISP. Using DDE or ActiveX
       [21.3] (entmod),(entmake) Layers, without (command "_LAYER"...)
       [21.4] How to select multiple files in LISP? (as in FILES-Unlock)
       [21.5] Replace multiple blocks
       [21.6] (vports), VIEWPORT entity, pixel conversion
       [21.7] Select all visible objects: zoom coordinates
       [21.8] How to write XYZ data of selected objects to a file?
     [22] Block Attributes
       [22.1] How to access block attributes?
       [22.2] How to MODIFY block attributes? DATESTAMP.LSP
       [22.3] How to UPDATE block attributes?
       [22.4] How to ENTMAKE a Block Complex Entity in AutoLISP
     [23] Polylines
       [23.1] How to access polyline VERTICES?
       [23.2] How to JOIN multiple lines to polylines?
       [23.3] Change WIDTH of multiple polylines
       [23.4] Create a polyline or spline: with (ENTMAKE) or (COMMAND)
       [23.5] How to calculate the LENGTH of polylines?
       [23.6] How to revert the polyline direction?
       [23.7] How to get the CENTER of a polyline?
     [24] Circle/Arc Geometry:  BULGE conversion, some trigonometry
     [25] DCL: listboxes with tabs or monotext font
     [26] EED Extended Entity Data: Get and Store
       [26.1] Select objects on their EED with (ssget "X")
       [26.2] Get EED from an object
     [27] How to break a command in LISP?
       [27.1] How to do an unlimited number user prompts?
     [28] How to decode ACIS internal geometry with LISP
     [A] Disclaimer, Notes from the author
+      [A.1] FAQ Locations
     [B] Acknowledgements
     [C] Recent Changes

Subject: [0] The Future of AutoLISP? Should I learn it or VB instead? AutoLISP will be definitely supported in future releases. VB was introduced to simplify Office Automation: ACAD <-> Excel/Access Both languages have advantages and disadvantages. You should take a look at both. VB seems to be more graphical and AutoLISP more logical. The object concept of VBA seems to be easier to learn, but you cannot run commands like in AutoLISP. The new VBA (>= R14.01) is extremely fast. See also [5.2] The future of AutoLISP already is Visual Lisp. For VLISP see [5.3] URL's:,, also [0.1] below. [0.1] What changed with AutoCAD 2000? The name :) No, there's much more, but you may call it Release 2000, R15 (though 15 is the version number and not the release number), A2000 or abbrevated A2K. The new Visual Lisp kernel (formerly "Vital Lisp") replaced the old xlisp-based AutoLISP kernel. What problems should you expect with Visual Lisp in R2000? (only the bad news). At I compiled a white paper. The major points are: Stricter error checking on loading, ACAD.LSP vs ACADDOC.LSP, You cannot/need not compile to ARX anymore, Incompatibilities AutoLISP - Visual LISP: Lisp functions are atoms no lists anymore, Protected symbols, Better exception handling, Pathname of the loaded VLX?, vl-export-symbol -> vl-doc-set, long acad symbol table names: EXTNAMES ActiveX automation, Variants and SAFEARRAYs, FAS4 cannot be loaded on R14. [0.2] Why cannot I create ARX anymore? With AutoCAD 2000 you cannot do that anymore as with ViLL or VLISP 4. Instead you compile to VLX (Visual Lisp Extension), which has basically the same functionality as the old Visual Lisp/Vital Lisp ARX, with the following differences: * You'll have to (load) the app. Before you had to (arxload) it. - Pro: Initialization is easier. The VLX doesn't abort completely on any error while loading. Before the whole ARX crashed with mysterious errors. - Pro: VLX are much smaller because they don't carry the whole Lisp environment, the VLRTS, along. Instead there's only one environment, VL.ARX, distributed with acad itself. So you can ship much smaller applications. - Contra: With loaded VLX there's no easy way to get the pathname of the app. Before it was possible with (arx) or (vl-exe-filename) * VLX has the option of seperate or common namespaces. With seperate ARX you had only the option of seperate namespaces (in fact completely seperate lisp environments). - Pro: This means that you can now choose the fastest and most secure compilation mode (LINK, DROP) and still keep common namespaces. (most of my apps benefit from this. I seperated my apps into one main module and several smaller ones) - Pro: ARX is only compatible per release, thus completely incompatible! VLX is new and therefore compatible only to newer releases (R16,...) but as lisp application it is by far more compatible than a ARX app. * Loaded ARX apps with (arx) return the pathname, loaded VLX apps with (vl-list-loaded-vlx) only a symbol, no path. This is a design flaw. You don't need ARX modules anymore. This is a feature, no bug.
Subject: [1] Where can I find AutoLISP routines on the Internet? The big AutoCAD tools sites with LISPs are: "AutoCAD Plugin Store" by This is the by AutoDESK "officially recommended" tools site. "CADalog" - The AutoCAD Shareware Clearinghouse (Mike Clark) "The CAD Depot", formerly known as "cadsyst" or "Rolling Stock Software", (David Whynot) recently bought by They are specialized in AutoCAD related software and have a very good AutoLISP collection. Other professional AutoLISP shareware sites post their URL's to the newsgroup too. Other relevant sites are: TenLinks ( and the UpFront ( ezine are the best CAD news services. Autodesk also started their portal site "Point A" at Some more sites with AutoLISP collections are: The CAD Users Webring xarch AutoCAD Info & Tools (Reini Urban) (with search) CADalyst magazine code (compiled by "Hot Tip Harry" Art Liddle) (with search) Owen Wengerd Terry Dotson + AcadX + + Paul Turvill + Vladimir Nesterovsky | Theo L.A. Groenenberg The CADshack (Jeff Foster) | Lisp Factory (Jay Garnett) Rakesh Rao - AutoCAD Tech Center Older or broken links: AutoCAD Tech Journal code (Peter Sheerin) (old) CADENCE magazine code (Peter Sheerin) | (fixed) UCCB AutoCAD and AutoLISP page (Paul Standing) (broken) McNeel's old lisp archive | (fixed) Dr.Lisp Utilities (Alexander Medwedew) (fixed) SimTel - Coast To Coast - Archive (fixed, really very old stuff) | | At (moved) were documents from the Autodesk Product Support answering technical questions. (Their FAQ's) + The ASA (Support Assistance, some kind of FAQ) was once at +, an improved but + slow tool is now at [1.1] Are the comp.cad.autocad articles stored somewhere? There is no comp.cad.autocad archive or such a thing, but there are some search machines which store news articles. In particular: | * - The biggest news archive | formerly known as * * * Phoaks - People Helping One Another Know Stuff - Automatic Links Extractor The Autodesk discussion forums have also a search feature at | Some specific older news postings are also stored at [1.2] Autodesk's SDK Up to Release 12 a Software Development Kit was available directly at Autodesk. The SDK1-2 was shipped with the international R12 for free. It included a lot of ADS and AutoLISP source code and libraries. From R13 on Autodesk provides a special developers network, comparable to Microsoft's, the ADN. The CD's are comparable to the old SDK but are more targeted to ObjectARX developers. Contact your nearest Autodesk headquarter for becoming a member. Some LISPs are at In the US, ADN membership costs $600.00 per year. The CDs don't include any SDK per se, but most of the stuff in the original SDKs is included in one form or another. (Owen)
Subject: [2] What are the best books to learn AutoLISP? AutoLISP to Visual LISP Kevin Standiford, Autodesk Press, ISBN 0-7668-1517 AutoLISP: Programming for Productivity, William Kramer, Autodesk Press, ISBN 0-8273-5832-6 Essential AutoLISP, Roy Harkow, Springer-Verlag, ISBN 0-387-94571-7 AutoLISP in Plain English, A Practical Guide for Non-Programmers, George O. Head, Ventana Press, ISBN 1-566-04140-6 AutoLISP Reference Manual Autodesk Press. Up to R12 there was a separate AutoLISP Reference book. Then AutoLISP became a part of the Customization Guide for R13. From R14 on this guide is compiled as Winhelp. Maximizing AutoLISP Rusty Gesner, Tony and Mark Middlebrook, Tony Tanzillo. A new Maximizing AutoLISP R13/R14 will be published hopefully sooner or later. But the R12 book is still worth buying, though it's difficult to find. More at There is a lot more AutoLISP books around. Recommended general LISP books (not AutoLISP!) are: ANSI Common Lisp, (Common Lisp primer) Paul Graham, Prentice Hall, ISBN 0-13-370875-6 Structure and Interpretation of Computer Programs, (high-level Scheme) H.Abelson, GJ. Sussman, J. Sussman, MIT Press, ISBN 0-262-01153-0 "This undoubtedly one of the best general computer books ever written." LISP, 3rd Edition, Patrick Henry Winston and Berthold Klaus Paul Horn, Addison-Wesley Publishing Company, ISBN 0-201-08319-1 Looking at LISP, Tony Hasemer, Addison-Wesley Publishing Company, ISBN 0-201-12080-1 [2.1] Online AutoLISP documents, Winhelp [deleted] [2.2] AutoLISP Coding Style Most of the samples being published by magazines or at various websites are written badly making the AutoLISP learning process even harder for newbies. LISP is hard to read anyway because of it's briefness and countless parentheses. Everybody is enforced to write clear, readable code. Autodesk's samples are quite well written but sometimes overdone. :) Automatic pretty printers, or so called beautifiers (see [6.3]) automatically format the code according to some kind of standard. On the R12 CD-ROM in the SDK2 ACG.DOC or at is an excellent Autodesk documentation about coding, commenting and intentation standards to keep lisp code readable. The most important points are: * Comment your code using ";;;" at row 1, ";;" inside the code (indented) and ";" for trailing comments (at row 39) * Follow the indenting standards as given by the pretty printers to be able to write better structured code, which is more readable. esp. for SETQ, DEFUN, IF, COND, PROGN * Try to avoid global variables. If you use them (for efficiency), to clarify, place asterics around them in uppercase, i.e: *GLOBAL* * Don't forget to localize your variables (behind "/" in the DEFUN parameter list). Only for debugging purposes you may want to undefine them temporarly. * Name protection: Since AutoLISP provides no protected name space, it's easy to overwrite even system functions. Use unique short prefixes at least when you publish or give away your code. I use UR- for functions and UR: for variables. The ADGE and Autodesk forces even 4 letter prefixes. Then your names are safe from being overwritten by other kamikaze functions. * Always use the leading underscore with any string (commands and options) given to COMMAND and OSNAP. There are even enough commercial programs which do not work on international versions. (command "_PEDIT" ss "_J") is better than (command "PEDIT" ss "J") * Don't do too much SETQ's: LISP was originally a functional language, without any variables. There are enough constructs which work efficiently with lists without the need of storing values intermediatly in symbols. (see code samples [22]...) But for readability and debugging purposes you should always set symbols. * An old LISP rule is: Any good function is not longer than 6 lines :) (LISP is the second oldest computer language, invented by John McCarthy at the MIT in 1958) * Prefer CONS over APPEND: three CONS and one REVERSE is better than one APPEND. For tricks with APPEND (omitting NIL) see esp. Serge's samples: i.e. REMOVE at [11] or the style comparison at [23.1]) * Try to use English symbols and comments * Don't use T, MIN, MAX or LAST as symbols! These are system functions!
Subject: [3] How do I debug AutoLISP programs? [3.1] There are some native AutoLISP debuggers: * Visual Lisp by Autodesk and Vital Lisp Professional support it in the IDE (the best), * ACOMP for R10 had one, (free) you can still use it with R12 DOS, but then you've got only the R10 LISP functions, i.e. no WCMATCH function, * Ld, AutoLISP Debugger for R14, R13c4 and R12/DOS from CZ, (free) at See "[5] AutoLISP compilers" [3.2] Modular style, TRACE The best support you can have for debugging is write your code in a well designed, modular style, pulling out distinct tasks into separate functions and then liberally using nested function calls. This will allow you to use the TRACE function as needed to locate any errors. [3.3] You may include BREAK functions and debug-print into your source code. Examples: ;;; Debugging functions (defun break (s) (if *BREAK* (progn (princ "BREAK>> (stop with <Enter>)\nBREAK>> ")(princ s) (while (/= (setq s (getstring "\nBREAK>> ")) "") (print (eval (read s))))))) (defun dbg-print (s) ;accepts atoms and lists (if *DEBUG* (if (listp s) (MAPCAR 'print s) (print s)))) (defun C:DEBUG () (setq *DEBUG* (not *DEBUG*))) ;switch it on and off (defun C:BREAK () (setq *BREAK* (not *BREAK*))) (defun CONT () (setq *BREAK* nil)) ;cont. without any interruption For a usage example see:
Subject: [4] How can I protect my AutoLISP programs? "You really have to protect it? If you just want to share routines with friends, why not give them the code? Working with others can be a great way to get new ideas and lead to a better application. Some of the best utilities were improved by my friends or I have improved some of my friends utilities." (Dennis) [4.1] Kelvinate with KELV.EXE (on the R12 CD-ROM or at the AutoLISP sites "[1]"). Free. De-Kelvinate LISP's with any pretty printer, see [6.3]. Symbol names (functions and variables) will stay garbled and comments are lost. [4.2] Protect with PROTECT.EXE (on the R12 CD-ROM or at the AutoLISP sites "[1]") Note that unprotectors exist. Free. [4.3] Kelvinate and Protect First kelvinate, to make it unreadable, then protect. Free. [4.4] Convert Shareware LISP En-/Decryptor by Maciej Lukasiewicz, Sweden. With Convert encrypted "Protected Lisps" cannot be decrypted by other programs, but by Convert it can. [4.5] ACOMP AutoLISP compiler ACOMP.EXE, on the R12 international release or at the AutoLISP sites. Free. More docs about ACOMP are at See also [5.1] [4.6] Vital LISP Professional Formerly at [broken] Say "ViLL". Outdated. See also [5.2] [4.7] Lisp2C LISP to C converter, for R12/R13/R14 Dos/Win (Watcom, Metaware, MSVC Libs). You need to own such a C/C++ compiler. Quite expensive. [4.8] Visual Lisp by Autodesk say "VLISP". see [5.3] FAS Security: There was recently a lengthy discussion about FAS security at both newsgroups. Apparently FAS can be decompiled to readable source code, but this tool is not available on the net yet. Rumors say that MNC files can also be decompiled for years now but this doesn't exist the net either. Linked and dropped FAS/VLX (compiled with Optimized/Internal) is similar to Kelvination. Symbol names, strings and numbers are more insecure than algorithms. Summary: Serious encryption is only done with Vital LISP and its successors. Kelvinating makes LISP files unreadable and load faster. Protected lisp files can be easily decrypted. With Convert -e$GUARD encrypted LISPs can be unprotected only with Convert.
Subject: [5] AutoLISP compilers There are three AutoLISP compilers, better ones could maybe used in the future. Some Lisp and Scheme platforms already do or will support ActiveX or just a simple FFI. [5.1] ACOMP ACOMP was supported up to R12 for the international releases only. It is free, and doesn't work with R13 nor with domestic R12/Win. It produces .BI4 files and needs special ACADL.EXP supplied as ACADLC.EXP See [5.2] Vital LISP Professional by Basis Software Inc. USA. Basis doesn't continue developing Vital Lisp anymore. License-free runtime modules for R12/R13/R14 DOS/Windows/NT See Some dealers still have it on stock. The latest version was 3.2. The R14 version (ViLL 3.x) includes ActiveX (like VB) and reactor support. See also [6.1] and [4.6] [5.3] Visual Lisp by Autodesk VLISP 4 (for R14), the successor of Vital Lisp, is basically the same as ViLL 3.2, only the GUI, some function names and the docs changed: vill- => vlisp-, the vlx- => vl- prefixes. Some vlax- funcs have more hyphens. With AutoCAD 2000 VLISP replaced the old AutoLISP engine. See [0.1] VLX files are packaged FAS files with optional DCL resources, used by R14/R15. AutoCAD 2000 FAS/VLX are incompatible with previous releases (FAS2 -> FAS4) because of added language features (seperate namespaces) [5.4] Better ones: Common Lisp and Scheme Native ARX exists for Corman Common Lisp (a simple console), COM support for Allegro Common Lisp 5, Lisp Works for Windows and in the future for GambitC. Via a FFI ("Foreign Function Interface") almost every lisp or scheme can communicate with AutoCAD. See Little work is done with Corman Lisp and ACL5, one commercial product uses ACL5 ("Design++" by Design Power See for more. Summary: AutoLISP compilers are bytecode compilers needing a runtime system. AutoCAD 2000 uses VLISP now, so the runtime system is included. You cannot create standalone programs, though ViLL/Vlisp (<=R14) creates a stand-alone ARX. The symbols are encrypted.
Subject: [6] AutoLISP editors and other tools [6.1] AutoLISP editors Visual Lisp by Autodesk see [5.3]. The best and most recommended tool. With AutoCAD 2000 it is included for free. Emacs for NT Huge editor and quite hard to learn but it's written and customizable in LISP. Free, for all platforms. Comes in two flavors, or the GNU emacs for NT. Check out Vital LISP outdated by Visual Lisp. Not available anymore LispLink 2000 Commercial AutoLISP Editor with Syntax Highlight, Parenthesis Checking, Project Manager, Dialog Preview, and Support for Visual LISP Functions and FAS Compilation. CodeMagic Shareware text editor with AutoLISP syntax highlighting. Old stuff: LispPad AutoLISP Editor by Tony Tanzillo. Visual LISP by WSSW Old small Windows LISP Editor, Version 1.0 was even free. See [1] WCEDIT 2.02 Old ADS editor for DOS R12, can evaluate lisp code from within the editor, free. See [1] CODEKEY Old commercial DOS IDE, internal pretty printer, protect, unprotect, kelvinator. Still available? ALLY 3.0 and CADET Shareware LISP Analyzer and Editor. See [6.2] pred free, small dos editor which provides parenthesis highlighting. At A similar editor is ADE. LSPEDIT from xlisp-stat A simple free Windows Lisp editor that supports parenthesis matching and code indentation. Check out General customizable programming editors like MultiEdit Pro, WinEdit, E!, PFE, TextPad, UltraEdit or PFE are widely used also. They usually don't provide Lisp syntax checking or pretty printing, but (some even regular expression) multi-file search/replace and customizable syntax highlighting. There are others not that good (ADE) nor I don't have a description yet. [6.2] Analyzers, Packagers and Parenthesis checkers Parenthesis checkers should not be used anymore. Editors should do the job. Analyzers generate a function cross-reference, the calling and the reverse callers tree. Packagers are used to generate libraries from various source files, copying all the needed functions. There's currently no code-walker which can internationalize command strings, but with R15 came a lisp analyzer (LCA). VLISP's [5.3] compiler analyses (compile with full messages) and checks parens <Ctrl-Alt-C> Reini's AutoLISP Packager Browsable function cross-referencer, reverse calling tree, creates a library from source files. ("Packaging" or "Function Shaker") PEI Findvars Similar to the Packager above, but not only functions, additionally detects symbols to be localized. I personally use this. RapidLisp v1.0c [new] Shareware Lisp analyser fr R14. AVC - AutoLISP Variable Collector [new] Freeware, finds all variables to be declared per function. LCA - Autodesk's AutoLISP Compatibility Analyzer On the Migration CD. Details AutoCAD 2000 compatibility issues found in specified AutoLISP (LSP) or Menu LISP (MNL) files. (simple "Code Walker") ALLY30.ZIP (old) Shareware LISP analyser. Checks syntax and prints statistics, function dependence tree and used symbols, but no packaging. At [1] (old) LCK LISP Checker 2.1b (graphical) (old) Simple PARNCH.ZIP (old) Simple There are also some AutoLISP programs which count parenthesis. [6.3] Pretty Printers External: FMT202S.ZIP LISP, DCL and FRM source code formatter. Not checked yet. LB.EXE Autodesk's source code beautifier. In the SDK2 or at [1]. Has problems with longer strings, and new-style in-line comments. PPRINT.LSP In the SDK2, see [1.2], or at [1] Internal: Visual Lisp, Vital LISP, Emacs and Codekey provide internal beautifiers as I'm aware of it.
Subject: [7] AutoLISP problems and bugs For AutoCAD 2000 and unexperienced VLISP users see [0.1]. There are almost no known serious AutoLISP bugs. The language interpreter itself (ACADL.EXE/.EXP, VLISP) works undoubtedly well. Some restrictions are based on the AutoCAD, ActiveX or the Proteus (DCL) engine. Some support LISP programs (i.e. DDMODIFY.LSP) are faulty sometimes. For Visual Lisp see the README.txt which lists all known bugs and limitations. Crashes with reactors are ACAD bugs. Two inofficial buglists are at: (the big one) (a private and short one) * LDATA by Tom Berger (VLISP for R14 and A2000) In short: Don't use LDATA at all. It may destroy DXF and DWG's in A2000. It is also VERY hard to get rid of them. * List Arguments with DOTTED PAIRS Passed from AutoLISP to Visual LISP or back may loose the outer parens. See the Visual Lisp README (undocumented in Vital Lisp) * SINGLE ATOM LISTS returned incorrectly from EXTERNAL APPS Visual LISP can not distinguish between a LIST of a single atom (element), and a single atom returned from an external ObjectARX or ADS application. * ENTGET used with LWPOLYLINE, HATCH (R14 only) The Z coordinate (caddr (getval 10 ele)) is a random number and often causes a floating point exception because it may too low or too high. Workaround: see part 2, Subject [23.1] * ENTMAKE VERTEX by Terry Dotson (R14 only) A problem can occur during the process of using (entmake) to create polylines, you must assign the layer to each of the VERTEX definitions (which Autodesk has told us), but you must also assign the layer to the ending SEQEND. Absence of this will cause the SEQEND to end up on the current layer, which can be later frozen. Attempts to move this piece of geometry will then cause a EREGEN error and crash in R14 (only). * ACAD_STRLSORT: Strange sort order in Windows. The chars in Windows are not sorted on its ASCII representation! Windows: (acad_strlsort '("-1" "+1")) -> ("-1" "+1"), DOS: (acad_strlsort '("-1" "+1")) -> ("+1" "-1") Both: (mapcar 'ascii ("-" "+")) -> (45 43) More at * AI_PROPCHK (ai_propchk) was renamed to (C:AI_PROP) in the R13c3 update patch. "The AutoLISP function ai_propchk has been changed to c:ai_prop so that it behaves similarly to other commands. This allows pressing return to bring back DDMODIFY if selected from the toolbar." * Faulty action callbacks in R13 DCL code crash AutoCAD There is a bug in R13 where AutoCAD crashes with a Fatal Error if an error occurs in AutoLISP code during an action callback from a scroll bar in a dialog box. For instance, if you try to evaluate a null function during the callback, AutoCAD crashes instantly. Technically, this isn't a bug in the AutoLISP interpreter, but we would still call it an AutoLISP bug. * You cannot rely on bitvalue 64 in flag 70 in symbol tables anymore since R13, but in all previous releases. Inserted blocks may have 64 not set. What else? See the unofficial AutoCAD buglist compiled by Steve Johnson for more faulty AutoLISP programs and behaviours, at * Protected LISP Files In pre-c4a R13 protected LISP files didn't stay protected in memory. In our opinion, this problem needs to be made known to all, so developers don't inadvertently assume their protected code is safe from prying eyes. This FAQ topic caused a major problem in moderated CompuServe's AutoCAD Forum. * Limited number of open selection sets They are intermediatly stored in temporary files. Get rid of not needed selection sets with setting the symbols to nil and run (gc), the garbage collector, which actually closes those files then. The maximal number depends on the operating system, i.e. in DOS of the FILES= value in CONFIG.SYS. R13 improved the number. * Numbers: range, accuracy, numerical precision Integer numbers are internal long fixnums (signed, 32-bit), but the communication from AutoLISP to AutoCAD accepts only 16-bit short fixnums, in the range -32768 .. +32767, because AutoCAD needs only short fixnums. Floating point numbers are doubles (64-bit IEEE). All internal AutoLISP and AutoCAD numerical calculations work with this double format, which should be sufficient. At least the first 14 decimal places are exact. A common problem is the confusion betwen the actual number (exact) and the rounded string representation. The number which is shown on the command-line is always the rounded string which takes care of LUPREC and DIMZIN. However with geometric comparisons there often occur round off errors, so that it's wise to compare points with a small fuzz factor [1e-12..1e-6]. (equal pt1 pt2 1e-6) ; 0.000001 rounding error tolerance instead of (equal pt1 pt2), esp. with angles. See also VB: It was also reported lately, that with certain automation controllers loaded, numerical accuracy and locale issues (`, vs `.) had undesirable sideeffects. A solution and explanation of this problem is pending. (Mostly in `, as decimal delimiter countries such as Germany) * ACOMP's (EQ) strictness With [5.1] ACOMP's compiled code you have to take care that the (EQ) behaviour in BI4's is much stricter than in plain AutoLISP. In AutoLISP (eq "1" "1") is T where in ACOMP's compiled code it's nil. The following are not real bugs, that make AutoLISP crash or return false results. They are just bad language implementations. * AND and OR should return the value of the not-NIL argument instead of T. See * MAX and MIN should handle string types too, because < and > accept and process strings types too. * see ACAD_STRLSORT above. * for stack overflow errors see [14]
Subject: [8] Sorting with AutoLISP In short: use VL-SORT (generic) or ACAD_STRLSORT (strings only), but beware: VL-SORT removes duplicate entries (which are EQ)! I've set up a AutoLISP sort overview at In LISP the mostly used sort method is merge sort (also used in (str-sort) in AutoDesk's TABLES.LSP sample) because that's a natural method for linked lists. Normally (e.g. in C) you use heap sort (for any data) or qsort (for random data) and insertion sort for the small lists (< 7) or sublists within the algorithm. There is a LISP code for shell-sort, bubble-sort, insertion-sort, quick-sort available for any data, lists of lists and indeces to lists. In LISP you can pass the predicate function to sort which is evaluated at run-time (here called 'method'). That's why you need only one sort function for multiple data types (i.e. numbers, points on x or y, strings, ...) (sort data method) ;method: less-than-predicate ;default for numbers: '< Some sample timings from sorting 100 elements: bubble sort : 13.639008 sec/ 30.08% insertion sort: 13.368042 sec/ 29.48% (fast for sorted lists) shell sort : 13.478973 sec/ 29.73% (poor implementation) merge sort : 2.232971 sec/ 4.92% quick sort : 2.433960 sec/ 5.37% vl-sort : 0.099976 sec/ 0.22% (Visual/Vital LISP internal) acad_strlsort : 0.089996 sec/ 0.20% (AutoLISP internal, strings)
Subject: [9] Recursion This is not an often asked question but a very interesting one, because LISP itself is defined recursively and it's often the easiest way to articulate hard problems. There some fine documents about recursion at especially the tutorial by Dennis Shinn. It explains in great detail: (defun fact (n) (cond ((zerop n) 1) (T (* n (fact (1- n)))))) Note: There's also a self-modifying example of this function explained at
Subject: [10] Iteration with MAPCAR,... Same as with recursion this is not a often asked question, but it's quite hard to understand too. Iterative statements in AutoLISP are: WHILE, REPEAT, FOREACH and MAPCAR. We use them widely in this FAQ code because they allow brief code. There's a short course in LAMBDA, QUOTE, MAPCAR... by Vladimir Nesterowsky: >> "There are 14 paths and 12 pigs. >> How can there be 24 ducks?" >> Is there a lisp command that will allow me to pick these >> lines of text, and recognize the number(s) in each line, >> in order to, say, raise each number by two? >> Leaving the sentence structure, etc, intact? This is one way. (I am sure there are many other ways) (defun mult2 (strng) ; by Vladimir Nesterowsky (strlgather (mapcar '(lambda (s / n) (if (zerop (setq n (atof s))) s (rtos (* n 2)))) (strlparse strng " ")) ; parse by spaces " ")) ; gather back with spaces is explained at ;;; flip rows and columns in a matrix (defun transpose(l) ; by Doug Wilson (apply 'mapcar (cons 'list l))) is explained at
Subject: [11] S::STARTUP, My LISPs aren't loaded at startup anymore LISP files can be loaded at the startup using LOAD in ACAD.LSP. Some LISPs, required with a menu to work, should be loaded from the corresponding <menu>.MNL file. The <menu>.MNL file - if different - should load ACAD.MNL LISP functions calling commands at the startup should be defined in S::STARTUP of ACAD.LSP. This function is called at the startup after the initialization automatically. Otherwise you'll get the "Command list interruption (6 . 2)" errors. Note: (command) may be safely called from within MNL files. (S::STARTUP) is mainly used to check for partial menus now. If the file name was provided without an extension the LOAD function assumes .LSP. If - without a path prefix, the usual AutoCAD library path is used, which is 1) The current directory 2) The directory containing the current drawing file 3) The directories defined in the ACAD environment variable (setup in the Preferences box, SUPPORT paths) 4) The acad.exe directory If your program isn't loaded anymore automatically, check your AutoCAD library path settings. With ACADLC (of ACOMP) and the domestic release of AutoCAD R12 ACAD.LSP is not loaded automatically. Therefore you must append (load "ACAD" -1) to your ACAD.MNL. Sample ACAD.LSP: ;;;ACAD.LSP ;;; Fred the Beaver, 12/12/94 (load "init" -1) ; this loads some tools of mine (defun S::STARTUP () (load "new-end" -1) ; this redefines the END command ) The -1 argument provides LOAD from interrupting the startup process, if any LOAD failure (causing an AutoLISP error). If a failure at the load-time occurs, -1 is returned, but the evaluation does not stop. -1 can be any expression as well. Sample code to enhance S::STARTUP in your code. With Visual LISP compiled code this will not work, it must be defined with DEFUN-Q instead. Functions are generally no lists anymore! Better than to use DEFUN-Q for S::STARTUP is to check for known hooks, a list of user-defined functions which are inserted and evaluated at run-time. (defun MY::STARTUP () ;your startup code goes here ;.. (princ)) (setq S::STARTUP (if (and S::STARTUP (listp S::STARTUP)) ;already defined in ; ACAD.LSP or elsewhere (append S::STARTUP (cdr MY::STARTUP)) ;append your code MY:STARTUP)) ;just your code or a simple one: (if (and S::STARTUP (listp S::STARTUP)) ;usually called consp (setq S::STARTUP (append S::STARTUP (list func '(princ)))) (setq S::STARTUP (list nil func '(princ)))) + Vladimir Nesterovsky: The main difference now in A2K+ versions is that functions defined with DEFUN are now a new datatype, USUBRs, and not lists as before. But when the function is defined with DEFUN-Q, it is a list still, like in previous versions. Here's the utility function to use that works in both cases: (defun plug-into-startup (funcname) ;by VladimirNesterovsky "to be called with quoted function name" (eval (list 'defun 's::startup () (if s::startup (list (list 'quote s::startup))) (list funcname)))) So if you have all your startup code packed into one routine (defun my-startup () (alert "My Startup")) You make it work with the call (plug-into-startup 'my-startup) Inside your code that is executed on startup, e.g. acaddoc.lsp or whatever. See also "[12] How to Autoload my programs?"
Subject: [12] How to Autoload my programs? How to load my programs automatically? You can either load your whole program at startup (see "[11] My LISP doesn't load at startup anymore") which needs more time and memory at startup time, or you can define them via the autoloading mechanism. From R14 on ARX programs use a new autoloading scheme (called "demand loading") with some registry settings and not from ACADRxx.LSP anymore. Look at the end of your ACADRxx.LSP how AutoCAD autoloads its programs. ;;;===== AutoLoad LISP Applications ===== ... (autoload "dline" '("dline" "dl")) ... This defines the commands DLINE and DL in the list to be loaded from the file DLINE.LSP when the user first calls the command DLINE or DL. Before that the function is simply defined like this one: (defun C:DL () (load "DLINE")(C:DL)) In fact the definition is more complicated because of error handling. After the first call the function is overwritten with the definition in the program. Advantages of autoloading: * Startup is faster, because you dont have to load all your lisp files. You just define the simple *wrapper* definition as above. This is done by the (autoload) function. * You need less memory. Disadvantages: * On errors in your program you will fall into a never ending loop, which will only stop after a stack overflow or Ctrl-C Note: with ACOMP compiled code even Ctrl-C is impossible. Insert then a call to an uncompiled (princ) somewhere. * You have to define and maintain all command names from your program in the autoloader definition. Changes to the lisp filename or the command name will cause the above error. Where to put your (autoload) definitions? * Not to ACADR13.LSP. * Well we recommend putting it to an initialization file of yours and not to ACAD.LSP because this is often changed by different applications and ACAD.LSP should be kept rather small. I.e. put it to a AUTOLOAD.LSP or INIT.LSP, which is loaded from ACAD.LSP. See "[11] My LISP doesn't load at startup anymore" * It should be mentioned that users should *not* modify ACADRxx.LSP. Since ACAD.LSP is not overwritten during upgrades, it is guaranteed to remain safe. In addition (as we saw with the R13c4a patch) if the ACADR13.LSP file has been modified, then the patch process may refuse to update it, thus resulting in program malfunctions.
Subject: [13] How can I pass a variable number of arguments to a lisp function? With plain AutoLISP this is not possible. You can either pass all your arguments in a list like this: ;;; print a variable number of arguments (of any type) (defun my-princ (x) ;; simple version, for better stuff look at the SDK2: PRINTF.LLB (if (listp x) (mapcar 'princ x) (princ x))) Or you have to define the function in ADS and export it to AutoLISP. Then you are free to write: (ads-print "Hello " "World " 1 2 3) or even (ads-printf "Hello %s %i %i" "World" 2 3) Look at Reini Urban's and Vladimir Nesterovsky's ADS samples at for implementations of the above examples. Official wishes were pointed to Autodesk regarding &optional as AutoLISP language enhancement, but it was not implemented in R14.
Subject: [14] How can I avoid stack overflows? In old AutoLISP the stack size was hardcoded. It couldn't be extended, but its size should be sufficient for most purposes. In the Visual Lisp IDE the stack overflow is simulated at 984 recursions, on the A2000 commandline or loaded programs outside the IDE there's no overflow anymore. This is dangerous on recursion errors of yours, see [9]. Most stack overflow errors occur on a program error of yours, preventing the system from falling into an endless loop, or from using recursive functions on large lists. Therefore you are limited to quite short lists with recursive functions and old versions. You cannot decrease your used stack size with using less local parameters in your recursive function! However do not use APPLY, EVAL or MAPCAR to call your function recursively, because they eat up the stack. Using tail recursion doesn't help either. You have to convert your recursive function to a iterative one. (There is a mathematical theorem that says, that every recursive function can be converted to a iterative one, tail-recursive ones even automatically.) Iterative versions may use stack-like functions like (push) and (pop), but those versions store the stack on the heap (autolisp node space), which size is only limited by your amount of virtual memory available. You can test the stack overflow with this simple function: ;;; create a list of n numbers (zero based) (defun intlst (l n) (cond ((zerop n) l) (T (intlst (cons (1- n) l) (1- n))))) and try: (setq n 100)(while (intlst nil (setq n (+ 10 n)))(print n)) In AutoLISP of R12/DOS you reach the stack limit with (intlst nil 138), in A13/Win with (intlst nil 240), in ACOMP bi4's with (intlst nil 1240), in Vital LISP/Visual Lisp IDE with (intlst nil 984). With R10c10, the first dos extended lisp version, you could enhance the lisp stack size with the environment variable LISPSTACK. ACOMP for R10 had COMPSTACK. With Vital LISP or Visual LISP RTS or A2000 (outside the IDE) the stack size is unlimited. Conversion to an iterative version yields the required results: (defun intlst (n / l) (repeat n (setq l (cons (setq n (1- n)) l)))) ;this looks ugly but it works
Subject: [15] (command "ROTATE3D") does not work! Why? Some commands are no internal AutoCAD commands, they are simple AutoLISP programs beginning with C: even if they are defined in ADS programs. Only native Rx applications (or now with vlax-add-cmd) export true commands. A list of all these commands are found in ACADRxx.LSP in the AUTOLOAD section. (see also "[12]") All these commands have to be called with (C:ROTATE3D) instead of (command "ROTATE3D"). However ADS functions may take optional arguments. See the customization manual for more. i.e. (c:rotate3d ss p1 p2 angle) is also valid, even (rotate3d ...)
Subject: [16] LISP programs operating over multiple drawings "I am having trouble getting a lisp file that will open a drawing and continue running. Once the new drawing is opened the LISP file ceases to exist in the Autocads memory. It has to be reloaded to recognise the commands." LISP memory is reloaded on a per drawing basis. There are some ways to execute a LISP on multiple drawings: 1) via a script that executes on multiple files. MYSCRIPT.SCR: (load "mylisp") _QSAVE _OPEN !nextdwg (load "mylisp") _QSAVE _OPEN !nextdwg ... 2) External 3rd party software such as RunLisp, ScriptPro or DDSCRIPT automate step 1. 3) R14 has a new feature, called 'Persistent LISP'. Set it in Preferences-Compatibility-Persistent LISP 4) Vital LISP has a built-in variable to act as Persistent LISP: (setq *VILL-NEW-FULL-INIT* nil) ;keep symbols between sessions 5) same with Visual LISP: (setq *VLISP-NEW-FULL-INIT* nil)
Subject: [17] How to export Visual Lisp functions to AutoLISP/AutoCAD? C: functions are automatically exported to AutoLISP. Plain vlisp/vill lisp functions must be exported either with (vl-acad-defun funcname) or their symbols may be exported with a special compiler pragma, defined either in the LSP file or in the GLD (global declarations) file. Better use special prefixes for such functions. .GLD: (AUTOEXPORT-to-ACAD-PREFIX ;| name prefixes for functions to be autoexported to AutoCAD: (strings) |; "myx-*" ) or one by one .LSP: (pragma '((export-to-acad myx-func1 myx-func2))) Note: There may exist known bugs in vlisp and vill with lists of atomic symbols and dotted pair lists in such functions arguments and return values. See [7]. Functions exported by external apps which are used in your application must be defined via XDF. Symbols (variables) whose values are updated in Visual Lisp and which values are also used in AutoLISP or AutoCAD (the menu e.g.), first may be marked for the compiler to be external with: (pragma '((not-localize myx:symbol))) but the value must be exported with (vlisp-export-symbol 'myx:symbol) each time the value is changed in Visual Lisp and control is returned to AutoCAD to be able to get the latest value in AutoLISP or in AutoCAD with !myx:symbol You may forget this whole chapter with AutoCAD 2000, however you might need to export your function from the protected namespace then with VL-DOC-SET. See also
Subject: [A] Disclaimer, Notes from the authors If you think of questions that are appropriate for this FAQ, or would like to improve an answer, please send email to Reini Urban <> but don't expect an reply. This AutoLISP FAQ is Copyright (c) 1996,97,98,99,2000 by Reini Urban. This FAQ may be freely redistributed in its entirety without modification provided that this copyright notice is not removed. It may not be sold for profit or incorporated in commercial documents (e.g. published for sale on CD-ROM, floppy disks, books, magazines, or other print form) without the prior written permission of the copyright holder. Permission is expressly granted for this document to be made available for file transfer from installations offering unrestricted anonymous file transfer on the Internet and esp. to be included into the official AutoCAD FAQ. The sample code is, if not otherwise stated, (c) 1996,97 by Reini Urban and may be freely used, but not sold. The basic functions in [20] are, if not otherwise stated, (c) 1991-97 by Reini Urban and may/should be freely used. If this FAQ is reproduced in offline media (e.g., CD-ROM, print form, etc.), a complimentary copy should be sent to Reini Urban, X-RAY, Nibelungeng. 3, 8010 Graz, Austria This article, the contents and the sample code, is provided AS IS without any expressed or implied warranty. [A.1] FAQ Locations Homepage of the HTML'ified version: + Annotated AcadWiki version: + The posted ascii versions (and always latest versions) are at and The Winhelp version (zipped with faq and code) is at The FAQ usenet archive is at resp. The LISP code from this FAQ is at See also the cca glossary for common abbrevations at Submissions for a new AutoCAD FAQ are stored at A french translation of the FAQ was made by Roger Rosec A japanese translation of the FAQ was made by MASAMI Chikahiro A russian translation by Igor Orellana at A german translation by myself at + A new spanish translation by Eduardo Magdalena + A greek translation is in progress. Relevant AutoDesk FAQ's and TechSupport AutoDesk news groups news:// New WebX interface at -- Reini Urban, Jun 25, 2002

User Contributions:

Mar 17, 2023 @ 5:17 pm
Regardless if you believe in God or not, read this message!!!

Throughout time, we can see how we have been carefully conditioned to come to this point where we are on the verge of a cashless society. Did you know that the Bible foretold of this event almost 2,000 years ago?

In the book of Revelation 13:16-18, we read,

"He (the false prophet who deceives many by his miracles--Revelation 19:20) causes all, both small and great, rich and poor, free and slave, to receive a mark on their right hand or on their foreheads, and that no one may buy or sell except one who has the mark or the name of the beast, or the number of his name.

Here is wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man: His number is 666."

Referring to the last generation, this could only be speaking of a cashless society. Why so? Revelation 13:17 states that we cannot buy or sell unless we receive the mark of the beast. If physical money was still in use, we could buy or sell with one another without receiving the mark. This would contradict scripture that states we need the mark to buy or sell!

These verses could not be referring to something purely spiritual as scripture references two physical locations (our right hand or forehead) stating the mark will be on one "OR" the other. If this mark was purely spiritual, it would indicate both places, or one--not one OR the other!

This is where it comes together. It is amazing how accurate the Bible is concerning the implantable RFID microchip. Here is information from a man named Carl Sanders who worked with a team of engineers to help develop this RFID chip:

"Carl Sanders sat in seventeen New World Order meetings with heads-of-state officials such as Henry Kissinger and Bob Gates of the C.I.A. to discuss plans on how to bring about this one-world system. The government commissioned Carl Sanders to design a microchip for identifying and controlling the peoples of the world—a microchip that could be inserted under the skin with a hypodermic needle (a quick, convenient method that would be gradually accepted by society).

Carl Sanders, with a team of engineers behind him, with U.S. grant monies supplied by tax dollars, took on this project and designed a microchip that is powered by a lithium battery, rechargeable through the temperature changes in our skin. Without the knowledge of the Bible (Brother Sanders was not a Christian at the time), these engineers spent one-and-a-half-million dollars doing research on the best and most convenient place to have the microchip inserted.

Guess what? These researchers found that the forehead and the back of the hand (the two places the Bible says the mark will go) are not just the most convenient places, but are also the only viable places for rapid, consistent temperature changes in the skin to recharge the lithium battery. The microchip is approximately seven millimeters in length, .75 millimeters in diameter, about the size of a grain of rice. It is capable of storing pages upon pages of information about you. All your general history, work history, criminal record, health history, and financial data can be stored on this chip.

Brother Sanders believes that this microchip, which he regretfully helped design, is the “mark” spoken about in Revelation 13:16–18. The original Greek word for “mark” is “charagma,” which means a “scratch or etching.” It is also interesting to note that the number 666 is actually a word in the original Greek. The word is “chi xi stigma,” with the last part, “stigma,” also meaning “to stick or prick.” Carl believes this is referring to a hypodermic needle when they poke into the skin to inject the microchip."

Mr. Sanders asked a doctor what would happen if the lithium contained within the RFID microchip leaked into the body. The doctor replied by saying a terrible sore would appea (...)

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