electric-indent-mode is enough to keep your code nicely aligned when all you do is type. However, once you start shifting blocks around, transposing lines, or slurping and barfing sexps, indentation is bound to go wrong.

aggressive-indent-mode is a minor mode that keeps your code always indented. It reindents after every command, making it more reliable than electric-indent-mode.

• An example of Lisp mode (Emacs Lisp):

• An example of non-Lisp mode (C++):

This package is available fom Melpa, you may install it by calling

M-x package-install RET aggressive-indent

Then activate it with

(add-hook 'emacs-lisp-mode-hook #'aggressive-indent-mode)
(add-hook 'css-mode-hook #'aggressive-indent-mode)

You can use this hook on any mode you want, aggressive-indent is not exclusive to emacs-lisp code. In fact, if you want to turn it on for every programming mode, you can do something like:

(global-aggressive-indent-mode 1)
(add-to-list 'aggressive-indent-excluded-modes 'html-mode)

If you don't want to install from Melpa, you can download it manually, place it in your load-path along with its two dependencies:

• Names
• and cl-lib.

Then require it with:

(require 'aggressive-indent)