Michael’s Corner

Michael's Corner is a monthly publication written by Michael E. Beall, Autodesk Authorized Author and peripatetic AutoCAD trainer. Michael travels all over the USA, bringing his fantastic experience and great understanding of AutoCAD to his clients. Michael's Corner brings together many of the tips, tricks and methods developed during these training sessions for the benefit of all users.

Michael's Corner provides something for every AutoCAD user. Every month, a number of articles cover a wide range of topics, suitable for users at all levels, including "The Basics" for those just starting out. Essentially, the aim of Michael's Corner is to help all AutoCAD users work smarter and faster.

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From the Vault

Originally published January 2008

Command Aliases and Options

Reference file: Acaddoc.lsp

Command aliases allow you to quickly access commands by typing in a few letters instead of the full command name or locating the command on one of the user interfaces. While command aliases are great for accessing commands, they do have one limitation and that is they cannot be defined with command options. To workaround this issue, you can define commands with AutoLISP that have a name with a couple letters. For example, if you want to perform a Zoom Window you need to start the ZOOM command and then use the Window option or click Zoom Window in the user interface, but with AutoLISP you could define a command named ZW to do the same thing.

Once the command is defined, you can automatically load it each time AutoCAD starts up by creating a file with the special name Acaddoc.lsp, or create an AutoLISP file with a name of your choice and then add it to the Startup Suite in the Load/Unload Application dialog box.

Instructions to create a simple Custom Command with AutoLISP

1. Start the Notepad text editor; click Start[All] ProgramsAccessoriesNotepad.
2. In Notepad, enter the following text:

;; Defines two commands: one performs a zoom window
;; and the other a zoom previous
(defun c:ZW () (command "._zoom" "_w"))
(defun c:ZP () (command "._zoom" "_p"))

3. From the menu bar, choose FileSave As….
4. In the Save As dialog box, select "All Files" from the Save As Type drop-down list.
5. Browse to one of AutoCAD's support paths or add a new support path on the Files tab of the Options dialog box. Enter the name Acaddoc.lsp in the File Name box and then click Save.
6. Switch to AutoCAD. Then save any files that are open and close AutoCAD.
7. Restart AutoCAD and create a new drawing. Then type ZW or ZP at the command prompt. If Acaddoc.lsp was found by AutoCAD the new commands should work.

The example (defun c:ZW () (command "._zoom" "w")) breaks down as follows:

(defun c:ZW () - The Defun function creates a new command that can be typed at the command prompt named ZW.

(command "._zoom" "_w")) - The Command function tells AutoCAD that you are using the following commands and options. So the example uses the ZOOM command with the Windows option.

The lines that start with a ; (semicolon) designate lines in the file that are used as comments and do not get executed or loaded into AutoCAD.

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