Trailing Whitespace Tips (was: Re: starting to review the Extend NOT NULL representation to pg_constraint patch)

Tom Lane <tgl@sss.pgh.pa.us> writes:
> * Lots of bogus trailing whitespace.  "git diff --check" can help you
> with that.

This is a repetitive common remark that I think sharing tips to avoid
that problem is a good idea. Here's an emacs setup to have trailing
whitespace hurt the eyes, and more-than-80 columns lines too. This one
is more controversial as we find lots of long lines in the PostgreSQL
sources. Still:

;; display only tails of lines longer than 80 columns, and
;; trailing whitespaces
(require 'whitespace)
(setq whitespace-line-column 80
      whitespace-style '(face trailing lines-tail empty))

;; face for tabs long lines' tails
(set-face-attribute 'whitespace-tab nil
		    :background "red1"
		    :foreground "yellow"
		    :weight 'bold)

(set-face-attribute 'whitespace-line nil
		    :background "red1"
		    :foreground "yellow"
		    :weight 'bold)

;; activate minor whitespace mode when in some coding modes
(add-hook 'emacs-lisp-mode-hook 'whitespace-mode)
(add-hook 'python-mode-hook 'whitespace-mode)
(add-hook 'c-mode-hook 'whitespace-mode)

Now, it's easy to find some more about it, including images of how it
looks. You can't miss trailing whitespace any more :

  http://ruslanspivak.com/2010/09/27/keep-track-of-whitespaces-and-column-80-overflow/
  http://panela.blog-city.com/python_and_emacs_4_whitespace_tabs_tabwidth_visualizi.htm
  http://www.emacswiki.org/emacs/WhiteSpace

I suppose people using other editors or tools will come up with other
tricks and tips. Maybe it should go in src/tools/editors/emacs.samples,
too?

Regards,
-- 
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support