Re: f90 comments indentation

[Glenn Morris]

Stefan Monnier wrote:

>> I am writing f90 programs and I have turned auto-fill mode on. I
>> want my comments to be indented to where my earlier comment line
>> starts. So, for example, what I want is this (irrespective of the
>> comment column)
>
>> real, (kind=long), dimension(3,3) :: abcd ! This is a test
>>                                           ! comment
>
>> But, what I get is
>
>> real, (kind=long), dimension(3,3) :: abcd ! This is a test
>> ! comment
>
> If this is what you get after hitting SPC (which triggered auto-fill),
> then it's a bug that you should report with M-x report-emacs-bug

That would not be a bug, because by default (controllable through
f90-indented-comment-re) f90-mode indents "!" comments as code, not to
comment-column.

> If that's what you get after hitting TAB on the second line, then
> it's a problem with indentation of comments (which is sadly partly
> separate from the indentation that takes place during auto-fill) and
> there might be some convention that you need to follow (such as
> using some other comment marker, or using two or three ! or ...).

(setq f90-indented-comment-re "!!")

would get "!" comments indented to comment-column, but would not
necessarily align them as the OP wants (if the non-comment portion of
the first line extended beyond comment-column). There's no option in
f90 for that style, but there probably could (and maybe should) be. In
the meantime, combining the above setting with something like the
following seems to work:

(defadvice f90-indent-line (around set-comment-column activate)
  "Set comment-column so as to align consecutive trailing comments."
  (let ((comment-column comment-column)
        col f90-cache-position)
    (save-excursion
      (beginning-of-line)
      (skip-chars-forward " \t")
      (when (and (looking-at "!") (zerop (forward-line -1)))
        (setq f90-cache-position (point))
        (end-of-line)
        (while (and (f90-in-comment)
                    (search-backward "!" f90-cache-position t))
          (setq col (current-column)))
        (or (looking-at f90-indented-comment-re)
            (and col (setq comment-column col)))))
    ad-do-it))