AfraLISP - Learn AutoLISP for AutoCAD productivity

Loading AutoLISP Files

by Kenny Ramage

Note: One of the most important things to remember about loading AutoLisp Routines is to ensure that your Lisp files and any support files (i.e DCL Files; DAT Files; etc) are in your AutoCad search path. (I dedicate a directory to all my Lisp files and relevant support files.

There are numerous ways of loading AutoLisp Files :

Command Line Loading

The simplest is from the AutoCad command line.
The syntax for loading AutoLisp files is :

(load "filename")

The.lsp extension is not required.

Menu Loading

The following code samples are one way of loading AutoLisp files from a menu.

Pull Down Menu's :

T_Steel [Steel Menu]
T_Beams [Drawing Setup]^C^C^P+
(cond ((null C:DDSTEEL) (prompt "Please Wait...")(load "DDSTEEL")))

Toolbars :

TB_DDSTEEL [_Button("Steel", "STEEL.bmp",
(cond ((null C:ddsteel) (prompt "Please Wait...")(load "ddsteel"))) ddsteel

This method of loading Lisp files first checks to see if the routine is already loaded. If it is, it runs the routine. If it is not, it first loads the routine, then runs it. Clever Hey?

Acad.Lsp File

The Acad.Lsp file is a useful way of loading a library of AutoLisp routines.
Each time you start a drawing AutoCad searches the library path for an Acad.Lsp file. If it finds one, it loads the file into memory.

You could use the normal load function (load "filename") in your Acad.Lsp file but if an error occurs whilst attempting to load one of your routines, the remainder of the file is ignored and is not loaded.
Therefore, you must use the on failure argument with the load function :

(load "Lispfile1" "\nLispfile1 not loaded")
(load "Lispfile2" "\nLispfile2 not loaded")
(load "Lispfile3" "\nLispfile3 not loaded")

The .MNL File

The other type of file that AutoCad loads automatically is the .MNL file.

If you have a partial menu file it can also have it's own .MNL file. Just remember that the .MNL file must have exactly the same name as your partial menu file. (except for the .MNL extension, of course.)

You can load Lisp files from this file using the load function exactly the same as you did in the Acad.Lsp file.

Command Autoloader

When you automatically load a command from your Acad.Lsp file (or a .MNL file) the commands definition consumes your systems resources whether you actually use the command or not. The Autoload function makes a command available without loading the entire routine into memory.

(Autoload "Utils" '("Utils1" Utils2" "Utils3"))
(Autoload "DDSteel" '("DDSteel"))

This would automatically load the commands Utils1, Utils2 and Utils3 from the Utils.Lsp file and DDSteel from the DDSteel.Lsp file.

S::Startup Function

If the user defined function S::Startup is included in the Acad.lsp or a .MNL file, it is called when you enter a new drawing or open an existing drawing.

For example, say that you wanted to override the standard AutoCad LINE and COPY commands with versions of your own, your Acad.Lsp file would something like this :

(defun C:LINE ()
   .....Your Definition.....
(defun C:COPY ()
   .....Your Definition.....
(defun S::Startup ()
    (command "Undefine" "LINE")
    (command "Undefine" "COPY")

Before the drawing is initialised, new definitions for LINE and COPY are defined. After the drawing is initialised, the S::Startup function is called and the standard definitions of LINE and COPY are undefined.