GNU Info

(emacs-lisp-intro.info)Install

---

Next: Interactive Prev: defun Up: Writing Defuns

---

Enter node , (file) or (file)node

Install a Function Definition
=============================

   If you are reading this inside of Info in Emacs, you can try out the
`multiply-by-seven' function by first evaluating the function
definition and then evaluating `(multiply-by-seven 3)'.  A copy of the
function definition follows.  Place the cursor after the last
parenthesis of the function definition and type `C-x C-e'.  When you do
this, `multiply-by-seven' will appear in the echo area.  (What this
means is that when a function definition is evaluated, the value it
returns is the name of the defined function.)  At the same time, this
action installs the function definition.

     (defun multiply-by-seven (number)
       "Multiply NUMBER by seven."
       (* 7 number))

By evaluating this `defun', you have just installed `multiply-by-seven'
in Emacs.  The function is now just as much a part of Emacs as
`forward-word' or any other editing function you use.
(`multiply-by-seven' will stay installed until you quit Emacs.  To
reload code automatically whenever you start Emacs, see Note:
Installing Code Permanently.)

Effect of installation

Change a defun

How to change a function definition.