Re: Org-mode version 6.32trans and 6.21b; Strange interaction between whitespace-mode and cust. org-ellipsis

[Martin Pohlack <mp26@os.inf.tu-dresden.de>]

Carsten Dominik wrote:
> On Dec 3, 2009, at 10:34 PM, Martin Pohlack wrote:
> 
>> Carsten Dominik wrote:
>>> Hi Martin, this looks to me like a bug in whitespace.el, why does it
>>> override the display table org-mode is using?
>> Hmm, my understanding is that each buffer can have its own display
>> table, buffer-display-table.  whitespace-mode has to modify this table
>> (or install an own one) if it wants to do buffer-local modifications.
>> So I think it modifies org-mode's table but doesn't override it.
>>
>> My irritation is that by doing so, it does modifies some global state
>> that effects other buffers.
>>
>> A short look into org.el shows that org-display-table is never made
>> buffer local, so this data structure is shared across all org-mode  
>> buffers?
> 
> Yes, this is the idea, and it seems only logical to me.  So why
> do you want different settings in different Org buffers for
> whitespace?  So far I am unconvinced that creating a new
> table in each buffer with the right thing to do.

Ok, I have three argument to support this.

1. Let me start by describing a helper and how I use it.  This is a
   snippet from my init.el:

----8<---------------------------------------------------------->8----
;;;
;;; whitespace stuff
;;;
(when (require 'whitespace nil t)
  (require 'column-marker)

  (defvar cycle-whitespace-modes-state 0
    "whitespace mode states:
     0 -> no whitespace stuff,
     1 -> highlighting of stray whitespace, 72 & 80 column lines
     2 -> ws highlighting and identification for tabs and spaces (», ·)")
  (make-variable-buffer-local 'cycle-whitespace-modes-state)

  (defun my-cycle-whitespace-modes (&optional state)
    (interactive)
    (if state
        (setq cycle-whitespace-modes-state state)
      (setq cycle-whitespace-modes-state
            (mod (1+ cycle-whitespace-modes-state) 3)))
    (case cycle-whitespace-modes-state
      (0
       (whitespace-mode 0)
       (column-marker-1 -2)
       (column-marker-2 -2)
       (column-marker-3 -2))
      (1
       (whitespace-mode 0)
       (whitespace-mode 1)
       (column-marker-1 72)
       (column-marker-2 80))
      (otherwise
       (whitespace-mode 0)
       (whitespace-mode 1)
       (whitespace-toggle-options (list 'tab-mark 'space-mark))
       (column-marker-1 72)
       (column-marker-2 80))))

  (global-set-key [f10] 'my-cycle-whitespace-modes)

  (defun my-whitespace-modes-none () (my-cycle-whitespace-modes 0))
  (defun my-whitespace-modes-some () (my-cycle-whitespace-modes 1))
  (defun my-whitespace-modes-full () (my-cycle-whitespace-modes 2))

  (add-hook 'c-mode-common-hook         'my-whitespace-modes-some)
  ;…
  )
----8<---------------------------------------------------------->8----

I usually have whitespace mode active in a medium warning level
(my-whitespace-modes-some), which show whitespace at end of line etc.

Sometimes, I want to see all spaces and tabs in a single buffer
explicitly, e.g. for aligning stuff manually or debugging things
(my-whitespace-modes-full).

At other times, I want to deactivate all whitespace highlighting
(my-whitespace-modes-none), e.g., when dealing with long lines or when
crafting some ASCII drawings.

I make, all of these decision per buffer.


2. Whitespace-mode is usually buffer local.  Having it modify other
   buffers is irritating.  If global effects are desired there is the
   variable whitespace-global-modes


3. (whitespace-toggle-options …) is documented to modify the local
   buffer only.


Org's global display table de-localizes all of whitespace-mode's local
functionality.

Cheers,
Martin