Is LISP Still Used in AutoCAD?

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Is LISP Still Used in AutoCAD?

AutoCAD, the popular computer-aided design (CAD) software, has a long history of supporting customizations through programming languages. One such language that has played a significant role in extending AutoCAD’s functionality is LISP.

What is LISP?

LISP, which stands for “LISt Processing,” is a programming language that was developed in the late 1950s. It was designed to manipulate symbolic expressions and is known for its powerful list processing capabilities. LISP has been widely used in artificial intelligence research and various other domains.

LISP and AutoCAD

In the early days of AutoCAD, LISP became the primary language for creating custom applications and automating repetitive tasks. Its simplicity, flexibility, and ability to interact directly with AutoCAD’s internal data structures made it an ideal choice for customization.

Benefits of Using LISP in AutoCAD

  • Automation: With LISP, users can automate tasks by creating custom commands or routines that perform complex operations quickly and efficiently.
  • Extensibility: LISP allows users to extend AutoCAD’s functionality by adding new features or modifying existing ones to suit their specific needs.
  • Data Manipulation: Using LISP, users can easily access and manipulate various data elements within an AutoCAD drawing, such as entities, layers, blocks, attributes, etc.
  • User Interface Customization: LISP provides the ability to create custom dialog boxes, menus, toolbars, and other user interface elements to enhance productivity and ease of use.

Current Usage and Future

Although AutoCAD has introduced new programming interfaces like .NET and AutoLISP (a dialect of LISP), the original LISP language is still supported in the software. Many AutoCAD users continue to rely on LISP for their customizations due to its familiarity, extensive documentation, and a large community of experienced developers.

LISP Examples in AutoCAD

To illustrate the usage of LISP in AutoCAD, let’s consider a simple example. Suppose you want to create a custom command that draws a circle with a specific radius at the current cursor position:

(defun c:mycircle ()
  (setq radius (getreal "\nEnter circle radius: "))
  (command "circle" "_non" pause "_noradius" pause pause pause)
  (princ)
)

In this example, we define a new command named “mycircle” using the defun function. The getreal function prompts the user to enter the circle’s radius, which is stored in the variable “radius.” The command function then invokes the built-in AutoCAD command “circle,” passing the necessary arguments to draw the circle with the specified radius.

Conclusion

LISP continues to be widely used in AutoCAD for customizations and automation. Its ability to access and manipulate various elements within an AutoCAD drawing makes it an indispensable tool for many professionals working with CAD software. While newer programming languages have been introduced over time, LISP’s legacy and extensive support ensure its continued relevance in enhancing and extending AutoCAD’s capabilities.