[dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Richard Stallman]

Would someone please DTRT, then ack?  Please put the fix in Emacs 22
as well as the trunk.

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From: Dieter Wilhelm <dieter@duenenhof-wilhelm.de>
To: bug-gnu-emacs@gnu.org
Date: Wed, 18 Jul 2007 17:39:34 +0200
Subject: image-dired (tumme) database file not existing

Hi

please do:

1.) emacs -D -Q

2.) M-x image-dired (loading some directory)

3.) Then I'd like to comment some file (pressing c) in the
    *image-dired* buffer but I receive the following error message:

image-dired-write-comments: Opening input file: no such file or directory, /home/dieter/.emacs.d/image-dired/.image-dired_db

			    Dieter

In GNU Emacs 22.1.5 (x86_64-unknown-linux-gnu, GTK+ Version 2.8.20)
 of 2007-07-01 on debby
Windowing system distributor `The X.Org Foundation', version 11.0.70101000
configured using `configure  '--with-gtk''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Article

Minor modes in effect:
  shell-dirtrack-mode: t
  iswitchb-mode: t
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent input:
M-b M-b M-b C-b ' v e C-e SPC 8 - ) . C-j C-j <tab> 
D i e t e r C-p C-p C-e C-b C-b C-b C-b <backspace> 
, SPC t o SPC b e SPC s h u r e SPC <backspace> <backspace> 
<backspace> <backspace> <backspace> u r e SPC I ' <backspace> 
SPC <backspace> ' v e SPC m a d e SPC n o SPC i <backspace> 
m i s t a k e s SPC C-a d u m b SPC M-q <M-backspace> 
s t u p i d SPC M-q C-e C-j C-j T h a n k s SPC f o 
r SPC t u m m e SPC M-( <backspace> <backspace> C-d 
SPC ( a SPC <backspace> SPC c o n v e r t ) <left> 
<left> <left> <left> <left> <left> <left> <left> s 
l o w SPC M-b M-b f r o m SPC C-e . <left> <left> <left> 
<left> <left> <left> <left> <left> <left> <left> <up> 
<left> <left> <left> <left> <left> <left> <left> <left> 
<left> <left> <left> <right> <right> <right> <right> 
<right> <right> <right> <backspace> ; C-c C-c <up> 
<return> <f4> <f5> M-x b b <return> r i c h <return> 
<help-echo> <down-mouse-1> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <down-mouse-1> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <f1> <f2> C-x o <tab> <tab> <tab> <tab> 
<tab> C-n C-n C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p 
C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p 
C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p 
C-p <return> t t M-x e m a c s - r e <tab> <backspace> 
<backspace> b u <tab> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
r e p o <tab> o <backspace> r t - e m <tab> <retur
n>

Recent messages:
Saving file /home/dieter/Mail/archive/sent...
Wrote /home/dieter/Mail/archive/sent
Sending...done
Auto-saving...done
Formatting...done.
Type C-x 4 b RET to restore old contents of the bbdb-list window.
Follow the link. [5 times]
widget-button-press: Buffer is read-only: #<buffer *Article*>
Making completion list...
Loading emacsbug...done


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Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Thien-Thi Nguyen]

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() Dieter Wilhelm <dieter@duenenhof-wilhelm.de>
() Wed, 18 Jul 2007 17:39:34 +0200

   image-dired-write-comments: Opening input file: no such file
   or directory, /home/dieter/.emacs.d/image-dired/.image-dired_db

below is a quick patch (against the trunk).
here is a ChangeLog entry:

	* image-dired.el (image-dired-sane-db-file): New func.
	(image-dired-write-tags, image-dired-remove-tag)
	(image-dired-list-tags, image-dired-write-comments)
	(image-dired-get-comment, image-dired-mark-tagged-files)
	(image-dired-create-gallery-lists): Call new func.

does this give good results?

thi


___________________________________________________

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Index: image-dired.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/image-dired.el,v
retrieving revision 1.4
diff -c -r1.4 image-dired.el
*** image-dired.el	13 Jun 2007 00:05:24 -0000	1.4
--- image-dired.el	19 Jul 2007 14:00:33 -0000
***************
*** 869,879 ****
--- 869,896 ----
  ;;;###autoload
  (defalias 'tumme 'image-dired-show-all-from-dir)
  
+ (defun image-dired-sane-db-file ()
+   "Check if `image-dired-db-file' exists.
+ If not, try to create it (including any parent directories).
+ Signal error if there are problems creating it."
+   (or (file-exists-p image-dired-db-file)
+       (let (dir buf)
+         (unless (file-directory-p (setq dir (file-name-directory
+                                              image-dired-db-file)))
+           (make-directory dir t))
+         (with-current-buffer (setq buf (create-file-buffer
+                                         image-dired-db-file))
+           (write-file image-dired-db-file))
+         (kill-buffer buf)
+         (file-exists-p image-dired-db-file))
+       (error "Could not create %s" image-dired-db-file)))
+ 
  (defun image-dired-write-tags (file-tags)
    "Write file tags to database.
  Write each file and tag in FILE-TAGS to the database.  FILE-TAGS
  is an alist in the following form:
   ((FILE . TAG) ... )"
+   (image-dired-sane-db-file)
    (let (end file tag)
      (with-temp-file image-dired-db-file
        (insert-file-contents image-dired-db-file)
***************
*** 893,898 ****
--- 910,916 ----
  
  (defun image-dired-remove-tag (files tag)
    "For all FILES, remove TAG from the image database."
+   (image-dired-sane-db-file)
    (save-excursion
      (let (end buf start)
        (setq buf (find-file image-dired-db-file))
***************
*** 927,932 ****
--- 945,951 ----
  
  (defun image-dired-list-tags (file)
    "Read all tags for image FILE from the image database."
+   (image-dired-sane-db-file)
    (save-excursion
      (let (end buf (tags ""))
        (setq buf (find-file image-dired-db-file))
***************
*** 2038,2043 ****
--- 2057,2063 ----
  Write file comments to one or more files.  FILE-COMMENTS is an alist on
  the following form:
   ((FILE . COMMENT) ... )"
+   (image-dired-sane-db-file)
    (let (end comment-beg-pos comment-end-pos file comment)
      (with-temp-file image-dired-db-file
        (insert-file-contents image-dired-db-file)
***************
*** 2108,2113 ****
--- 2128,2134 ----
  
  (defun image-dired-get-comment (file)
    "Get comment for file FILE."
+   (image-dired-sane-db-file)
    (save-excursion
      (let (end buf comment-beg-pos comment-end-pos comment)
        (setq buf (find-file image-dired-db-file))
***************
*** 2136,2141 ****
--- 2157,2163 ----
  on all image files in the database file.  The files that have a
  matching tags will be marked in the dired buffer."
    (interactive)
+   (image-dired-sane-db-file)
    (let ((tag (read-string "Mark tagged files (regexp): "))
          (hits 0)
          files buf)
***************
*** 2300,2305 ****
--- 2322,2328 ----
  
  (defun image-dired-create-gallery-lists ()
    "Create temporary lists used by `image-dired-gallery-generate'."
+   (image-dired-sane-db-file)
    (let ((buf (find-file image-dired-db-file))
          end beg file row-tags)
      (setq image-dired-tag-file-list nil)

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Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Mathias Dahl]

> below is a quick patch (against the trunk).
> here is a ChangeLog entry:

> does this give good results?

I haven't tested the patch yet but it looks okay. I had a different
idea in mind, however:

Instead of making each function make sure a db file exist, why not
change code like this:

 (find-file image-dired-db-file)

into this:

 (find-file (image-dired-db-file))

And inside that new defun basically do what you did in your new function.

I did not follow very closely the recent discussions about Emacs' data
directory so I don't remember if anything useful came out of it that
could be used here.

Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Thien-Thi Nguyen]

() "Mathias Dahl" <mathias.dahl@gmail.com>
() Thu, 19 Jul 2007 17:03:09 +0200

   Instead of making each function make sure a db file exist, why not
   change code like this:

   (find-file image-dired-db-file)

   into this:

   (find-file (image-dired-db-file))

   And inside that new defun basically do what you did in your new function.

well, i considered that, too, but decided against it due to the
following reasoning (somewhat muddied by the summer heat):

there are two phases to the code's relationship w/ the file:
 0/ ascertaining that it exists;
 1/ accessing it.

i think it's best to keep these separate because the cost of phase
0 should be minimized.

when they are performed separately, a knowledgable programmer
(such as the author of image-dired.el ;-) can further decrease the
costs by avoiding phase 0 altogether in some places, by reasoning
about the call graph, where the unknowledgable programmer (me)
mechanistically added "safe" calls.  in other words, there is some
upside to the separate approach; it invites refined hacking.

when the phases are performed together, no such potential exists
(except in reworking the code to separate them; ie., inviting more
hacking than necessary :-).

of course, one could argue lots of file-exists-p calls are no big
deal, but i would not be that one.  (half-informed philosophical
mumbling follows) what we see here is the basic tension between
functional programming and the real world (external) state...
change happens but is it the root or the leaves that must react?

thi

Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[tomas]

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On Thu, Jul 19, 2007 at 05:37:10PM +0200, Thien-Thi Nguyen wrote:
> () "Mathias Dahl" <mathias.dahl@gmail.com>
> () Thu, 19 Jul 2007 17:03:09 +0200
> 
>    Instead of making each function make sure a db file exist, why not
>    change code like this:
> 
>    (find-file image-dired-db-file)
> 
>    into this:
> 
>    (find-file (image-dired-db-file))
> 
>    And inside that new defun basically do what you did in your new function.
> 
> well, i considered that, too, but decided against it due to the
> following reasoning (somewhat muddied by the summer heat):
[...]
> of course, one could argue lots of file-exists-p calls are no big
> deal, but i would not be that one.  (half-informed philosophical
> mumbling follows) what we see here is the basic tension between
> functional programming and the real world (external) state...
> change happens but is it the root or the leaves that must react?

Ah, philosophy, let's jump in ;-)

One aspect that IMHO deserves mention is that Mathias' approach is more
change-friendly. If a third, not-so-knowledgeable hacker (e.g. me) tries
to fix something, (s)he is less probable to screw things up.

Regards
- -- tomás
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Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Thien-Thi Nguyen]

() tomas@tuxteam.de
() Fri, 20 Jul 2007 05:25:44 +0000

   One aspect that IMHO deserves mention is that
   Mathias' approach is more change-friendly. If a
   third, not-so-knowledgeable hacker (e.g. me) tries
   to fix something, (s)he is less probable to screw
   things up.

sometimes screwing things up is the best change (at
least, temporarily ;-).  in this way the maintainer
gets to practice "stimulated annulling", yuk yuk.

thi

Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[tomas]

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On Fri, Jul 20, 2007 at 08:44:37AM +0200, Thien-Thi Nguyen wrote:
> () tomas@tuxteam.de
> () Fri, 20 Jul 2007 05:25:44 +0000
> 
>    One aspect that IMHO deserves mention is that
>    Mathias' approach is more change-friendly [...]

> sometimes screwing things up is the best change (at
> least, temporarily ;-).  in this way the maintainer
> gets to practice "stimulated annulling", yuk yuk.

:-))

- -- tomás
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Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Mathias Dahl]

> below is a quick patch (against the trunk).
> here is a ChangeLog entry:
>
>         * image-dired.el (image-dired-sane-db-file): New func.
>         (image-dired-write-tags, image-dired-remove-tag)
>         (image-dired-list-tags, image-dired-write-comments)
>         (image-dired-get-comment, image-dired-mark-tagged-files)
>         (image-dired-create-gallery-lists): Call new func.

Since there has been no strong objection (mine is more a philosophical
one and not a very strong one) I think we should install your fix. We
can always debate the differences later; the fix does solve the
problem and does not cause any problems as far as I can see.

Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Thien-Thi Nguyen]

() "Mathias Dahl" <mathias.dahl@gmail.com>
() Sun, 22 Jul 2007 01:36:02 +0200

   I think we should install your fix

thanks for reviewing the patch.  it's now
installed on both trunk and EMACS_22_BASE.

thi

Re: [dieter@duenenhof-wilhelm.de: image-dired (tumme) database file not existing]

[Richard Stallman]

Thanks for fixing it.