{"id":10781,"date":"2020-09-22T07:00:00","date_gmt":"2020-09-22T14:00:00","guid":{"rendered":"https:\/\/www.autodesk.com/blogs\/autocad\/?p=10781"},"modified":"2020-10-20T10:40:18","modified_gmt":"2020-10-20T17:40:18","slug":"autolisp-to-automate-your-tasks-part-1-beginner","status":"publish","type":"post","link":"https:\/\/www.autodesk.com/blogs\/autocad\/autolisp-to-automate-your-tasks-part-1-beginner\/","title":{"rendered":"AutoLISP to Automate Your Tasks: Part 1 – Beginner"},"content":{"rendered":"\n

I\u2019ll admit it. I just love AutoLISP, and I consider it my \u201chome\u201d language.<\/p>\n\n\n\n

But I also understand that my love of the language isn\u2019t universal. You may not consider yourself a programmer, or it might just be intimidating. It really doesn\u2019t have to be, and even with just minimal knowledge, you can still accomplish a lot.<\/p>\n\n\n\n

This three-part series<\/a> will help you become aware of the kinds of things you can do with AutoLISP at three levels of expertise: Beginner, Intermediate<\/a>, and Advanced<\/a>. Right now, we\u2019ll start at the very beginning.<\/p>\n\n\n\n

What a Beginner Should Know<\/h2>\n\n\n\n

I think it\u2019s important for any AutoLISP user to know what it is. LISP stands for LIS<\/span>t P<\/span>rocessing. That\u2019s your first clue. Everything in the language is a list in some form. You\u2019ll need to know about them, whether they\u2019re defined as a LIST, a CONS, a DOTTED PAIR, or an S-EXPRESSION (or just EXPRESSION for short).<\/p>\n\n\n\n

Of course, there are various data types you\u2019ll need to be familiar with. AutoLISP considers a LIST or a CONS as a data type. Others include STRINGS, REAL numbers, and INTEGERS.<\/p>\n\n\n\n

Note<\/u>: One of the reasons AutoLISP is so easy for non-programmers (people like us) is that you don\u2019t have to manage data types and memory allocation like other languages. There\u2019s no need to compile your code either. In fact, the interpreter is built into AutoCAD, so you can run expressions right from the Command Line.<\/em><\/p>\n\n\n\n

As for basic Terminology and Syntax, you should know that items within a list are ATOMS. The functions that AutoLISP uses are called\u2026FUNCTIONS\u2014that\u2019s easy! And FUNCTIONS sometimes require ARGUMENTS. Those are the ATOMS that follow the Function call in the expression.<\/p>\n\n\n\n

Syntax can be defined as the rules that any kind of language uses. The basic rules of AutoLISP are that everything is contained within a set of parentheses. Next, is that the function is always the first item (or ATOM) in a list.<\/p>\n\n\n\n

(functionName argument1 argument2 \u2026)<\/p>\n\n\n\n

Note<\/u>: It\u2019s important to note here that every Expression returns a value. That\u2019s an important point, as it sets AutoLISP apart from other languages that are considered \u201cProcedural\u201d languages. In the simplest terms, those languages execute a line of code, move on to the next, and so forth until complete. Without going into a dissertation on \u201cFunctional\u201d languages, just remember that while we may tend to use AutoLISP in a procedural manner within a CAD program, it is much more powerful than that.<\/em><\/p>\n\n\n\n

You should be aware that expressions can be nested, and that you evaluate them from the inside out.<\/p>\n\n\n\n

(functionName argument1 (functionName argument1 argument2) argument3 \u2026)<\/p>\n\n\n\n

A beginner should be aware of internal AutoLISP functions, especially DEFUN and SETQ. Others may include:<\/p>\n\n\n\n