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Autodesk has steadfastly refused to include the LISP interpreter in AutoCAD LT. Each time rumor of a new LT version hits the wire speculation is rife about whether or not LISP will be added ‘this time’.  There was even an authoritative assertion that AutoCAD LT 2000 would include LISP.  Apparently this was almost the case, but LISP was pulled at the last minute on instructions from Autodesk top brass.

LT began its days with quite a few elements of AutoCAD missing, to justify its considerably lower price, but it has gradually crept up so that now with 2000 it has just about everything from AutoCAD 2000 that 90% of users ever utilize – except for LISP.  As a relatively easy to use and powerful programmable interface to AutoCAD LISP is a crucial element in many AutoCAD based offices.  Unless solid modeling, rendering or raster image overlays are important to you, the only thing you get for the extra several thousand dollars cost of AutoCAD over AutoCAD LT is LISP.  That’s a mighty expensive customizing facility!

The most recent developer’s programming system for AutoCAD is ARX.  Of course ARX is also absent from LT, or is it?  If you look in the LT 2000 directory you see that as well as a 6Mb ACLT.EXE file there are numerous ARX files.  In fact, LT uses the ARX system for a lot of its own functionality.  It’s a fair bet that AutoCAD LT 2000 has ARX ‘hooks’ within it.

Making the most of the lack of LISP and the ARX hooks in AutoCAD LT 2000, drcauto of Sydney, Australia, has produced the LT Toolkit 200 add-on for LT 2000.  The toolkit is delivered partly as an ARX module adding the missing LISP facility.  It also uses several Windows DLL files.  Just the idea of using LISP in AutoCAD LT would be welcomed far and wide.  The best part is that it does work.

The LT Toolkit program installs like typical Windows applications, by running setup.exe. It installs into its own folder "C:\Program Files\LT_Toolkit\" by default, finds the location of your LT 2000 installation and sets up linkages to it.  It creates an icon on the desktop and a link in the Windows Start Menu, both of which run the LT Toolkit program.  LT 2000 is started by the LT Toolkit program, so that the only visible result of running LT Toolkit is a sign-on graphic announcing itself and then the familiar LT display.  LT must be started via the Toolkit for Toolkit facilities to be available.  If you click the original LT 2000 icon you get the original unmodified LT.

LT Toolkit does not make any visible changes to LT, which is a bit confusing.  I thought it hadn’t done anything at all at first.  It doesn’t even add any extra Help items.  Puzzled, I copied one of my LISP files into the local directory for ease of access and tried typing on the command line: (load "attribs.lsp"). Normally LT would respond with something like: "Error: Lisp unavailable".  But lo, my LISP program loaded and worked!

Well, that’s very good I thought, but it’s like loading LISP in ye olde AutoCAD v2.6 because you have to know the file’s name and full directory path and type it all correctly (which I suspected and the reason why I copied my .LSP file into the Toolkit folder).  I poked around all the menus but there was no sign of AutoCAD’s Applications Loader.  Taking a punt, I typed AutoCAD’s keyboard command for it: APPLOAD, and surprise, surprise, up popped a dialog box for finding and loading LISP programs, as shown here.  Now that really fills the bill.

The APPLOAD dialog in LT Toolkit, as you can see, has an upper panel that acts the same as a normal Windows folder navigation and file selection dialog.  Having located a LISP file and highlighted it, the Load button, which replaces the usual Open button, loads the LISP file the same as typing (load "filename").  The lower panel shows LISP files that have been loaded and their drive-folder location.  This is similar to the AutoCAD APPLOAD dialog except that the file-type drop-down will only filter for files of type LSP.  The AutoCAD one also loads ARX files.

So far, I had run the program from the LT Toolkit desktop icon.  When I looked in the Start menu, I saw that as well as the program item there was also LT Toolkit Help, and that popped up a quite extensive series of help screens that told all.  Be sure to find it and read it!

Then I noticed that the right mouse button pop-up menu was a bit different and has some extra tools, which are the rest of LT Toolkit, and include the APPLOAD command.  These extras include commands to copy-&-rotate or move-&-rotate selected objects, and to move or copy selected objects along the Z axis.  I had thought there ought to be some new menus as there are menu files in LT Toolkit’s folder.  Examining the MNU file I saw that it is in fact just the one pop-up menu.  There is also a DCL file that defines the APPLOAD dialog box, so obviously the system also supports DCL dialog box programming within LISP.  The additional copy and move commands are implemented as LISP files, and are also accessible by cryptic typed commands, as the Help explains.

I still thought it was a bit strange having to type APPLOAD, so I got into the standard ACLT.MNU file with my trusty text editor and added APPLOAD to the Tools Pull-down menu, just like it is in the ‘real’ AutoCAD.  I had never tried customizing LT menus before and wasn’t sure whether or not it would work.  But yes, it did, after I figured out a few obscurities of its menu load process.  But it had the unfortunate side effect of disabling the Toolkit’s right-click popup menu.  Drcauto advised that it had not implemented any LT menu changes because LT’s menu customizing system does seem to be a bit ‘flakey’.

The big thing is that LT Toolkit does add the ability to load and run LISP, which is what everyone has been clamoring for in LT for many years.  LT Toolkit sells for about A$495 in Australia, which may seem a bit dear for just adding LISP when LT 2000 itself costs about A$1,800, but when you consider that the ‘official’ solution costs over A$6,000, LT Toolkit quickly looks like a bargain.

drcauto