emacs lisp, how to get buffer major mode?

Question

I have tried to search Google and look in the manual, but still cannot find how to get major mode of a buffer object. Can you help me with an example or a reference. Thanks

only solution I could find was to query major-mode after changing the buffer and then changing back to original buffer. Is there a better way to do it?

score 45 · Accepted Answer · edited Sep 21 '12 at 05:19

45

Is there a problem with that?

(defun buffer-mode (buffer-or-string)
  "Returns the major mode associated with a buffer."
  (with-current-buffer buffer-or-string
     major-mode))

with-current-buffer will restore your buffer when it returns.

edited Sep 21 '12 at 05:19

haxney

3,358
4
30
31

answered Feb 10 '10 at 16:45

Aidan Cully

5,457
24
27

12

You could also do this with `(with-current-buffer buffer-or-string major-mode)` instead of `save-excursion`. – haxney Feb 11 '10 at 09:53
2

@haxney: Using `(save-excursion (set-buffer ..) ...)` is indeed deprecated in favor of `(with-current-buffer ...)`. The byte-compiler of Emacs-24 warns about such uses. – Stefan Sep 19 '12 at 20:12
@stefan: Where might an emacs noob see such deprecations? – Realraptor Jul 03 '18 at 15:01
As noted, the byte-compiler warns about it: just byte-compile your files, it will give you useful advice. – Stefan Jul 03 '18 at 17:08
It works, but I'm curious if emacs can handle this straightforward? Why should we change the target buffer shortly to current, apply function, and change it back? Why isn't there a function that takes a buffer and return its major-mode directly? Is it for some historical convention? Or there are deeper facts in emacs that prevent us doing that? – Student Apr 21 '20 at 01:51

score 41 · Answer 2 · answered Feb 16 '13 at 10:37

41

For current buffer:

(message "%s" major-mode)

answered Feb 16 '13 at 10:37

Adobe

12,967
10
85
126

score 36 · Answer 3 · answered Jul 15 '12 at 00:49

36

A simple way to do this is to use the buffer-local-value function since major-mode is a buffer-local variable:

(buffer-local-value 'major-mode (get-buffer "*scratch*"))

answered Jul 15 '12 at 00:49

Jeremie Pelletier

680
8
8

This actually answers the original asker's question. which is how to do this without switching buffers. – intel_chris Dec 04 '20 at 09:31

Brian Burns · Answer 4 · 2019-01-13T18:18:43.213

7

Just extending from previous answers - call with no arguments to get the current buffer's mode:

(defun buffer-mode (&optional buffer-or-name)
  "Returns the major mode associated with a buffer.
If buffer-or-name is nil return current buffer's mode."
  (buffer-local-value 'major-mode
   (if buffer-or-name (get-buffer buffer-or-name) (current-buffer))))

E.g. in *scratch* buffer:

(buffer-mode) => 'lisp-interaction-mode

(buffer-mode "tasks.org") => 'org-mode

edited Jan 13 '19 at 18:18

answered Mar 17 '14 at 16:52

Brian Burns

20,575
8
83
77

Thanks for offering a comprehensive solution! – Yu Shen Jan 12 '19 at 17:31

score 0 · Answer 5 · answered Feb 10 '10 at 16:42

0

Well, describe-mode takes an optional buffer argument, but that displays the help... and I'm not exactly sure what it returns...

But that's the best I could find in a brief search... sorry...

answered Feb 10 '10 at 16:42

Brian Postow

11,709
17
81
125

score 0 · Answer 6 · answered Sep 09 '18 at 20:05

0

Simply evaluate this:

(print major-mode)

answered Sep 09 '18 at 20:05

sidharth arya

245
3
11

alinsoar · Answer 7 · 2019-11-28T16:14:57.033

0

Another way, apart from directly readind the major-mode variable would be by directly readind the mode-name variable.

edited Nov 28 '19 at 16:14

answered Nov 28 '19 at 16:02

alinsoar

15,386
4
57
74

emacs lisp, how to get buffer major mode?

7 Answers7

Linked

Related