bug#4902: 23.1; directory-abbrev-alist is not handled early enough

[David J. Biesack]

Eli and Stefan;

Thanks for you assistance. I really appreciate the time you've spent
investigating this.

Obviously, the file naming structure
is far beyond my control and not something I can or want to change
(it would break far too many tools and processes). Suffice it to
say, it's something I have to live with.

I was able to achieve what I want with

(defadvice find-file-noselect (before
                               find-file-noselect-apply-abbreviations
                               (filename &optional nowarn rawfile wildcards)
                               activate)
  ;; normalize the file via (customize-variable 'directory-abbrev-alist)
  ;; *before* find-file-noselect calls (expand-file-name filename)
  ;; which puts C: at the front of paths.
  (ad-set-arg 0 (abbreviate-file-name filename))
)

and calling abbreviate-file-name in a couple other functions I use (my own
version of find-file-at-point etc.) At least, so far it is working as I expect.

I was aware of file-name-handler-alist from looking through cygwin-mount and had
considered that but it seemed complicated. I'll save the following suggestion
and install it if my own customizations prove insufficient.

djb

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> CC: <4902@emacsbugs.donarmstrong.com>
> Date: Wed, 11 Nov 2009 09:52:19 -0500
> 
> > Obviously, there are too many different names for the same file,
> > and I want Emacs to normalize all files to a canonical
> > form; i.e. all the variations of my network home should
> > be normalized to u:/ and so forth.
> 
> > directory-abbrev-alist:
> 
> > '(("^//dntsrc/u/sasdjb" . "u:")
> >   ("^/u/sasdjb" . "u:")
> >   ("^//sashq/root/u/sasdjb" . "u:")
> >   ("^/nfs/sanyo/vol/vol2/u22/sasdjb" . "u:/")
> >   ("^//sashq/root/u/sasdjb" . "u:")
> >   ("^/sas/" . "//dntsrc/sas/")
> >   ("^/sasgen" . "//dntsrc/sasgen/"))
> 
> The way I see it, the problem really is in the way you organize and use
> your naming structure.  So "the right solution" would be a combination
> of discipline, conventions, and symlinks to sort out this mess and make
> sure that you see much fewer variations of filenames and that all the
> ones you see work everywhere (via symlinks, for example).
> 
> Now, I understand this may not be practically feasible for you, but
> I think that changing Emacs to accomodate this particular situation is
> a bit hard to justify.
> 
> OTOH, Emacs does provide enough hooks already for you to be able to make
> it work, I think.  The hook you want is file-name-handler-alist.
> The only problem with it, is that it's very powerful and quite a bit
> trickier to use than directory-abbrev-alist.
> 
> You could try the code below (guaranteed 100% untested).
> 
> 
>         Stefan
> 
> 
> (defvar djb-filemess-remappings
>   '(("\\`/\\(/dntsrc/u\\|u\\|/sashq/root/u\\|nfs/sanyo/vol/vol2/u22\\)/sasdjb"
>      . "u:")
>     ("\\`/\\(sas\\(gen\\)?\\)/" . "//dntsrc/\\1/")))
> 
> (defun djb-filemess-run-real-handler (operation args)
>   (let ((inhibit-file-name-handlers
>          (cons 'djb-filemess-handler
>                (and (eq inhibit-file-name-operation operation)
>                     inhibit-file-name-handlers)))
>         (inhibit-file-name-operation operation))
>     (apply operation args))))
> 
> (defun djb-filemess-handler (operation &rest args)
>   (let ((fn (get operation 'djb-filemess-handler)))
>     (if fn (funcall fn operation args)
>       (djb-filemess-run-real-handler operation args))))
> 
> (defun djb-filemess-remap-1 (operation args)
>   (let ((file (car args))
>         (remappings djb-filemess-remappings)
>         newfile)
>     (while (and (null newfile) remappings)
>       (if (string-match (caar remappings) file)
>           (setq newfile (replace-match (cdar remappings) t nil file))
>         (setq remappings (cdr remappings))))
>     (djb-filemess-run-real-handler operation
>                                   (cons (or newfile file) (cdr args)))))
> 
> (put 'expand-file-name 'djb-filemess-handler 'djb-filemess-remap-1)
> (put 'substitute-in-file-name 'djb-filemess-handler 'djb-filemess-remap-1)
> 
> (dolist (remapping djb-filemess-remappings)
>   (push (cons (car remapping) 'djb-filemess-handler)
>         file-name-handler-alist))
> 
> 
> 


-- 
David J. Biesack, SAS
SAS Campus Dr. Cary, NC 27513
www.sas.com    (919) 531-7771