bug#24150: 25.1.50; New command: dired-create-empty-file

[Tino Calancha <tino.calancha@gmail.com>]

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On Thu, 4 Aug 2016, Clément Pit--Claudel wrote:

>Ah, so it's different from touch. Is there already a command in dired
>that sets the access and modification time of a file? If not, maybe
>this command could do it? I'm not sure it's useful to have the command
>fail if the file exists. If you go that, maybe renaming the command to
>eg dired-touch would be useful? Although I see the parallel with
>dired-create-directory, so maybe it's fine.

'dired-do-touch' doesn't create a new file.
I use to create an empty file with
M-! touch new-file RET
Note this creates a new file in the current directory; it
desn't create non existing parens, for instance:
M-! touch new-paren/new-file RET
;; touch: cannot touch 'new-paren/new-file': No such file or directory

The command i am suggesting is a partner of 'dired-create-directory':
it also creates the paren dirs.

>I think there's a slight problem with this sentence.  Maybe
>*** New command 'dired-create-empty-file' (similar to
>'dired-create-directory') creates a new empty file;
>bound to 'M-+'.
Thanks a lot!

> Do you think this could be a defun instead of a macro?
Of course, it should be a defun!
Following is the corrected patch to dired-aux.el
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diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index 4732d9c..f95e74e 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -1888,25 +1888,47 @@ dired-dwim-target-defaults
        dired-dirs)))


-;;;###autoload
-(defun dired-create-directory (directory)
-  "Create a directory called DIRECTORY.
-If DIRECTORY already exists, signal an error."
-  (interactive
-   (list (read-file-name "Create directory: " 
(dired-current-directory))))
-  (let* ((expanded (directory-file-name (expand-file-name directory)))
-	 (try expanded) new)
-    (if (file-exists-p expanded)
-	(error "Cannot create directory %s: file exists" expanded))
+(defun dired--create-empty-file-or-directory (fname &optional 
create-file)
+  "Create an empty file or directory called FNAME.
+If FNAME already exists, signal an error.
+Optional arg CREATE-FILE if non-nil, then create a file.  Otherwise 
create
+a directory. "
+  (let* ((expanded (directory-file-name (expand-file-name fname)))
+         (parent (directory-file-name (file-name-directory expanded)))
+         (try expanded) new)
+    (when create-file
+      (setq try parent
+            new expanded))
+    (when (file-exists-p expanded)
+      (error "Cannot create file %s: file exists" expanded))
      ;; Find the topmost nonexistent parent dir (variable `new')
      (while (and try (not (file-exists-p try)) (not (equal new try)))
        (setq new try
-	    try (directory-file-name (file-name-directory try))))
-    (make-directory expanded t)
+            try (directory-file-name (file-name-directory try))))
+    (cond (create-file
+           (unless (file-exists-p parent)
+             (make-directory parent t))
+           (write-region "" nil expanded nil 0))
+          (t
+           (make-directory expanded t)))
      (when new
        (dired-add-file new)
        (dired-move-to-filename))))

+;;;###autoload
+(defun dired-create-directory (directory)
+  "Create a directory called DIRECTORY.
+If DIRECTORY already exists, signal an error."
+  (interactive (list (read-file-name "Create directory: ")))
+  (dired--create-empty-file-or-directory directory))
+
+;;;###autoload
+(defun dired-create-empty-file (file)
+  "Create an empty file called FILE.
+If FILE already exists, signal an error."
+  (interactive (list (read-file-name "Create empty file: ")))
+  (dired--create-empty-file-or-directory file 'create-file))
+
  (defun dired-into-dir-with-symlinks (target)
    (and (file-directory-p target)
         (not (file-symlink-p target))))

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