Emacs Redux

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A Peek at Emacs 24.4: Auto-indentation by Default

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I’ve written in the past about electric-indent-mode, which was added in Emacs 24.1. In Emacs 24.4 one of the most prominent user visible changes is that it’s enabled out-of-the box. That’s a huge step towards the “modernization” of Emacs and one of the bigger changes to the defaults in recent times. Let’s review briefly how the mode works with a couple of Ruby examples (| signifies the cursor position). Without electric-indent-mode:

1
def something|

After you press Return you’ll get:

1
2
def something
|

With it:

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def something|

After you press Return you’ll get:

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2
def something
  |

Nice, ah?

One problem with electric-indent-mode is that it doesn’t play nice with some (mostly third-party) modes (yaml-mode, slim-mode, etc). I guess the situation will improve over time, but for now you can simply disable the mode in such problematic cases:

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(add-hook 'yaml-mode-hook (lambda () (electric-indent-local-mode -1)))

Note that electric-indent-local-mode was introduced in Emacs 24.4.

If you want to make a major mode electric-indent aware, have a look at the documentation of electric-indent-functions and electric-indent-chars.

P.S.

Dmitry Gutov recently wrote more on the topic in the context of ruby-mode in Emacs 24.4.

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