RE: Expanding list into string within a command

[arthur miller]

Maybe I was too fast, didn't show how to use macroexample:

(defmacro with-command (cmdname &rest args)

(dolist (arg args)

 .... do your thing here .... ))

Now when you use it :

(with-command ls -l -h -s)

If you really want to parse those args or do something with them. But I think 
it is better to build a string and pass them that way to a command.


-------- Originalmeddelande --------
Från: Jean Louis <bugs@gnu.support>
Datum: 2020-12-06 20:47 (GMT+01:00)
Till: Help GNU Emacs <help-gnu-emacs@gnu.org>
Ämne: Expanding list into string within a command


I would like to get this function to work, to convert geographical
coordinates notation from 5d15'57.76"S 35d8'22.65"E to decimal system
by using `proj' software and I wish to make generic function that will
accept any kind of format input to avoid hard coding.

This works well on command line:

$ cs2cs -f "%.6f" +proj=latlong +datum=WGS84 +to +proj=latlong +datum=WGS84
5d15'57.76"S 35d8'22.65"E
-5.266044       35.139625 0.000000

And I know how to make it when hard coded. Here I wish to expand it
maybe with macro.

This is the invocation of the function that I would like to get
working by feeding 2 strings, first being coordinates and second the
`cs2cs' format for conversions of coordinates.

(syogm-cs2cs "5d15'57.76\"S 35d8'22.65\"E" "-f \"%.6f\" +proj=latlong 
+datum=WGS84 +to +proj=latlong +datum=WGS84")

Error is:

"Rel. 6.1.0, May 15th, 2019
<cs2cs>:
missing argument for -f
program abnormally terminated
"
Error probably comes from lack of my knowledge how to use macro
expansion as here one could see how I have imagined that it could
expand:

(defun syogm-cs2cs (coord-string cs2cs-format)
  (let* ((command "cs2cs")
         (output (command-stream-in-out command coord-string `,(string-join 
(split-string cs2cs-format) " "))))
    output))

So I was thinking to use macro that will expand the list within a
command. Is there different better way to do this?

The below functions are related only in so far to maybe make these
above working.

This function here I could improve. This one is invoked many times by
many programs and I would not like changing it. One way to solve the
issue could be that I test for ARGS if it is list or not and convert
there.

(defun command-stream-in-out (command string &rest args)
  (let* ((uid (number-to-string (user-uid)))
         (memory-dir (rcd-memory-dir))
         (infile (concat memory-dir "command-input")))
    (string-to-file-force string infile)
    (with-temp-buffer
      (apply 'call-process command infile (current-buffer) nil args)
      (buffer-string))))

All below functions are only relevant for execution of above
functions.

(defun rcd-memory-dir ()
  (let ((xdg-runtime-dir (getenv "XDG_RUNTIME_DIR")))
    (if xdg-runtime-dir (slash-add xdg-runtime-dir)
      (if (and (file-directory-p "/dev/shm")
               (file-writable-p "/dev/shm"))
          (slash-add "/dev/shm")))))

(defun string-to-file-force (string file)
  "Prints string into file, matters not if file exists. Returns FILE as file 
name."
    (with-temp-file file
      (insert string))
    file)

(defun slash-add (path)
  "Adds slash `/` quickly on the end of string"
  (let ((last (substring (reverse path) 0 1)))
    (if (string= last "/") path
      (concat path "/"))))