Re: comments in cc mode

[Alan Mackenzie <acm@muc.de>]

Michael <mmassmann@econ.vu.nl> wrote:
> Dear Alan,

> On May 22, 11:43?am, Alan Mackenzie <a...@muc.de> wrote:
>> Hi, Michael,

>> "Massmann, M. (Michael)" <mmassm...@feweb.vu.nl> wrote:

>> > Dear Andreas,
>> > Many thanks for this. Could you point me to the documentation for the
>> > options available for comment-style? After playing around with some of
>> > them I did not get the desired effect.
>> > I also had a look at cc-mode's `c-indent-comment-alist' and set every
>> > single entry to `column' and `nil', so as to have the default column
>> > (ie 100) apply, no matter what the surrounding syntax is. The variable
>> > `c-indent-comments-syntactically-p' I set to nil so that it does not
>> > override the previous settings.
>> > This seems to have the desired effect that when I press M-; to insert a
>> > *new* comment on a line, empty or not, the comment indeed starts in
>> > column 100.
>> > Yet when I press M-; to re-align an *existing* comment, the entire
>> > comment is moved to a column other than 100 in 9 out of 10 cases.
>> > Any advice on how to rectify this problem would be appreciated. Thanks!

>> I've just gone through `comment-dwim' in edebug (the Emacs debugger), and
>> it seems like comments are being made to fit within `fill-column'. ?I
>> don't know why this is being done, but could you try setting it to a high
>> value, say

>> ? ? (setq fill-column 150)

>> . ?Does this solve the immediate problem? ?Does it introduce any new
>> problems?

>> > Regards,
>> > Michael

>> --
>> Alan Mackenzie (Nuremberg, Germany).

> Many thanks for your suggestion! This was precisely what was going
> pear-shaped. I did have my fill-column at 150 to start with, but some
> of my comments were more than 50 characters long, and they seem to
> have been shifted left such that they ended on column 150. I have now
> increased fill-column to 200 and everything works beautifully.

> One more question if I may: is there an easy way to tell Emacs to
> automatically set fill-column to 200 when in cc-mode and to leave it
> at 150 otherwise (eg when loading auctex)? Column 200 is off my screen
> and it is only with code comments that this doesn't bother me.

The following (not tested) should do it:

(setq-default fill-column 150)
(defun mm-cc-fill-column ()
  (setq fill-column 200))
(add-hook 'c-mode-common-hook 'mm-cc-fill-column)

> Thanks again for your help,

No problem.  I must say, you've got a MUCH wider screen than I have.  ;-)

> Michael

-- 
Alan Mackenzie (Nuremberg, Germany).