Re: patch: write-file to arbitrary target directory

[Eduard Wiebe <usenet@pusto.de>]

Richard Stallman <rms@gnu.org> writes:

> My point is that the normal practice is not to put the directory
> name in the buffer name.  Does this change have any effect on that
> usual case?

No. See below.

>     And if DIR is nil, read-file-name use 'default-directory'
>anyway.  (If i am not mistaken.)
>
> Please double-check.

It is so. Compare itself:

src/fileio.c:

DEFUN ("read-file-name", Fread_file_name, Sread_file_name, 1, 6, 0,
       doc: /* .... and `read-file-name-function'.  */)
     (prompt, dir, default_filename, mustmatch, initial, predicate)
     Lisp_Object prompt, dir, default_filename, mustmatch, initial, predicate;
{
  ...
    if (NILP (dir))
      dir = current_buffer->directory;

and src/buffer.c:


  DEFVAR_PER_BUFFER ("default-directory", &current_buffer->directory,
		     make_number (Lisp_String),
		     doc: /* ... */);

> If it works right for that reason, there should be a comment to
> explain.

I attached a new patch of function with some additional comments, and
for manual/docs. Please have a look a this.

Index: doc/emacs/files.texi
===================================================================
RCS file: /sources/emacs/emacs/doc/emacs/files.texi,v
retrieving revision 1.14
diff -u -r1.14 files.texi
--- doc/emacs/files.texi	20 Oct 2007 04:24:25 -0000	1.14
+++ doc/emacs/files.texi	18 Nov 2007 22:50:17 -0000
@@ -492,9 +492,10 @@
 (except that @kbd{C-x C-w} asks for confirmation if the file exists).
 @kbd{C-x C-s} used on a buffer that is not visiting a file has the
 same effect as @kbd{C-x C-w}; that is, it reads a file name, marks the
-buffer as visiting that file, and saves it there.  The default file name in
-a buffer that is not visiting a file is made by combining the buffer name
-with the buffer's default directory (@pxref{File Names}).
+buffer as visiting that file, and saves it there.  Is directory of file
+does not exist, you are asked for creating them. The default file
+name in a buffer that is not visiting a file is made by combining the
+buffer name with the buffer's default directory (@pxref{File Names}).
 
   If the new file name implies a major mode, then @kbd{C-x C-w} switches
 to that major mode, in most cases.  The command


Index: doc/lispref/files.texi
===================================================================
RCS file: /sources/emacs/emacs/doc/lispref/files.texi,v
retrieving revision 1.2
diff -u -r1.2 files.texi
--- doc/lispref/files.texi	6 Sep 2007 04:27:42 -0000	1.2
+++ doc/lispref/files.texi	18 Nov 2007 22:50:40 -0000
@@ -355,12 +355,13 @@
 @end deffn
 
 @deffn Command write-file filename &optional confirm
-@anchor{Definition of write-file}
-This function writes the current buffer into file @var{filename}, makes
-the buffer visit that file, and marks it not modified.  Then it renames
-the buffer based on @var{filename}, appending a string like @samp{<2>}
-if necessary to make a unique buffer name.  It does most of this work by
-calling @code{set-visited-file-name} (@pxref{Buffer File Name}) and
+@anchor{Definition of write-file} 
+This function writes the current buffer into file @var{filename},
+thereby creates all parent directories if necessary, makes the buffer
+visit that file, and marks it not modified.  Then it renames the buffer
+based on @var{filename}, appending a string like @samp{<2>} if necessary
+to make a unique buffer name.  It does most of this work by calling
+@code{set-visited-file-name} (@pxref{Buffer File Name}) and
 @code{save-buffer}.
 
 If @var{confirm} is non-@code{nil}, that means to ask for confirmation
@@ -370,7 +371,8 @@
 If @var{filename} is an existing directory, or a symbolic link to one,
 @code{write-file} uses the name of the visited file, in directory
 @var{filename}.  If the buffer is not visiting a file, it uses the
-buffer name instead.
+buffer name instead.  Interactively, the user is asked for
+creating of all parent directories of output file.
 @end deffn
 
   Saving a buffer runs several hooks.  It also performs format

Index: lisp/files.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/files.el,v
retrieving revision 1.941
diff -u -r1.941 files.el
--- lisp/files.el	16 Nov 2007 08:03:45 -0000	1.941
+++ lisp/files.el	18 Nov 2007 22:53:04 -0000
@@ -3075,8 +3075,10 @@
 the default file name but in that directory.  You can also yank
 the default file name into the minibuffer to edit it, using \\<minibuffer-local-map>\\[next-history-element].
 
-If the buffer is not already visiting a file, the default file name
-for the output file is the buffer name.
+If the buffer is not already visiting a file, the default file
+name for the output file is the buffer name. Are parent
+directories of output file not existent, the functon asks user
+for creating those.  Noninteractively this happens by default.
 
 If optional second arg CONFIRM is non-nil, this function
 asks for confirmation before overwriting an existing file.
@@ -3086,14 +3088,25 @@
    (list (if buffer-file-name
 	     (read-file-name "Write file: "
 			     nil nil nil nil)
-	   (read-file-name "Write file: " default-directory
-			   (expand-file-name
-			    (file-name-nondirectory (buffer-name))
-			    default-directory)
-			   nil nil))
+	   ;; If buffer name has directory parts, propose this
+	   ;; directory path for writing. Otherwise DIR is nil and we
+	   ;; use `default-directory' by default.
+	   (let ((dir  (file-name-directory (buffer-name)))
+		 (file (file-name-nondirectory (buffer-name))))
+	     (read-file-name "Write file: "
+			     dir (expand-file-name file dir) nil nil)))
 	 (not current-prefix-arg)))
   (or (null filename) (string-equal filename "")
       (progn
+	;; If directory of file is not existent, create it with all parents.
+	(let ((dir (file-name-directory filename)))
+	  (when (and dir (not (file-exists-p dir)))
+	    (and (interactive-p)
+		 (or (y-or-n-p
+		      (format "Directory `%s' does not exist; create? " dir))
+		     (error "Canceled")))
+	    (make-directory dir 'parents)))
+
 	;; If arg is just a directory,
 	;; use the default file name, but in that directory.
 	(if (file-directory-p filename)
   
Index: src/fileio.c
===================================================================
RCS file: /sources/emacs/emacs/src/fileio.c,v
retrieving revision 1.594
diff -u -r1.594 fileio.c
--- src/fileio.c	21 Oct 2007 10:53:16 -0000	1.594
+++ src/fileio.c	18 Nov 2007 22:54:52 -0000
@@ -6349,6 +6349,7 @@
 DEFUN ("read-file-name", Fread_file_name, Sread_file_name, 1, 6, 0,
        doc: /* Read file name, prompting with PROMPT and completing in directory DIR.
 Value is not expanded---you must call `expand-file-name' yourself.
+(If DIR is omitted or nil, the `default-directory' is used.)
 Default name to DEFAULT-FILENAME if user exits the minibuffer with
 the same non-empty string that was inserted by this function.
  (If DEFAULT-FILENAME is omitted, the visited file name is used,
  
-- 
Eduard Wiebe