Re: Function to find symlink target

[Jean Louis <bugs@gnu.support>]

* Emanuel Berg <incal@dataswamp.org> [2022-05-19 02:02]:
> Jean Louis wrote:
> 
> > (defun rcd-dired-find-symlink ()
> >   "Find target of a symlink"
> >   (interactive)
> >   (when (dired-get-marked-files)
> >     (let ((file (car (dired-get-marked-files))))
> >       (if (file-symlink-p file)
> > 	  (let* ((file (file-truename file))
> > 		 (directory (file-name-directory file))
> > 		 (file (file-name-nondirectory file))
> > 		 (back (length file)))
> > 	    (find-file directory)
> > 	    (search-forward file)
> > 	    (backward-char back))
> > 	(message "Not a symlink: %s" file)))))
> >
> > Let me know if I should improve this by any means.
> 
> Hello again Jean!
> 
> 1. Do auto-indentation ...

Thanks. Thought it indended in my file. Maybe email copy and paste
changed something.

> 2. `require' is needed for `dired-get-marked-files', do
>    byte-compile to find out and always do that before
>    posting here.

If you mean (require 'dired) that is in my file. I understand.

> 3. The defun has a confusing name, you have already found the
>    symlink one would think?

I will call it: `rcd-dired-show-symlink-target'

> 4. Emacs thinks of the docstring that the "[f]irst sentence
>    should end with punctuation". Always do the style check
>    before posting here BTW, here's an example how. [1]

OK. Like this:

(defun rcd-dired-show-symlink-target ()
  "Show target of a symlink."

> 5. `dired-get-marked-files' is invoked twice, instead just do
>     it once and reuse the result with and in `let'.


> 
> 6. "file" appears as a let-binding twice in `let*', confusing
>    and probably no good reason to do so either, right?
> 
> 7. I'm unsure but if you `find-file' a directory that is
>    already open in a buffer, you still end up at `point-min'?
>    If you don't, you need to got there before the search,
>    (goto-char (point-min)) as you know.
>    
> 8. Instead of doing `backward-char', do something like this:
>    [you can try it below as well]
> 
> (when (search-forward "key" (point-max) t)
>   (goto-char (match-beginning 0)) )

(defun rcd-dired-show-symlink-target ()
  "Show target of a symlink."
  (interactive)
  (let ((file (car (dired-get-marked-files))))
    (if (and file (file-symlink-p file))
      (let* ((target (file-truename file))
	     (target-exists (file-exists-p target))
	     (directory (file-name-directory target))
	     (target (file-name-nondirectory target)))
	(if target-exists
	    (progn
	      (find-file directory)
	      (when (search-forward target (point-max) t)
		(goto-char (match-beginning 0))))
	  (message "Target does not exist: %s" target)))
      (message "Not a symlink: %s" file))))

Yes, I have tried this, and now I see that finding is not accurate.

Example is this one:

S lrwxrwxrwx     1    8 May 22 16:15 test1.pdf -> test.pdf
  -rw-r--r--     1   90 May 22 15:24 basic.yml
  -rw-r--r--     1  15K May 22 15:13 test.pdf

as if I invoke function on first line it will come to -> test.pdf
which is not what I would like.

Then I have tried with this version, unsuccessfully:

(defun rcd-dired-show-symlink-target ()
  "Show target of a symlink."
  (interactive)
  (let ((file (car (dired-get-marked-files))))
    (if (and file (file-symlink-p file))
      (let* ((target (file-truename file))
	     (target-exists (file-exists-p target))
	     (directory (file-name-directory target))
	     (search (concat "\d\d " (file-name-nondirectory target))))
	(if target-exists
	    (progn
	      (find-file directory)
	      (when (search-forward-regexp search (point-max) t)
		(goto-char (match-beginning 0))))
	  (message "Target does not exist: %s" target)))
      (message "Not a symlink: %s" file))))

as for that version I think that at least 2 digits should be included
before the space when searching in Dired and I am doing something
wrong.


-- 
Jean

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