Re: User interface confusion; p0.30 invokes VM?

[Hallvard B Furuseth <h.b.furuseth@usit.uio.no>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> 	(when (and (file-exists-p
> 		    (setq file (expand-file-name command (pop path))))
> 		   (file-executable-p file))

Why file-exists-p?  Can a file be executable but not exist?

Also, don't search the path for absolute file names.

(defun mailcap-command-p (command)
  "Say whether COMMAND is in the exec path."
  (let ((path (if (file-name-absolute-p command) '(nil) exec-path))
 	file)
    (catch 'found
      (while path
 	(when (and (file-executable-p
		    (setq file (expand-file-name command (pop path))))
		   (not (file-directory-p file)))
 	  (throw 'found file))))))

However, neither version works on operating systems that append a file
type to command file names (.COM, .BAT, .EXE, whatever).  You can do it
in C, though.  Maybe you can get RMS to make lread.c:openp() available
to emacs-lisp commands.  Something like this (untested, a slight fix to
something I wrote a long time ago):


extern Lisp_Object Qidentity;

DEFUN ("locate-file", Flocate_file, Slocate_file, 0, 2, 0,
  "Find first FILE in PATH with one of SUFFIXES, checking EXEC-ONLY.
EXEC_ONLY is nil to find all files, t to only find executables.
PATH and SUFFIXES are lists or colon-separated strings.
SUFFIXES may also be t, then the system's suffixes for executables are used.")
  (file, path, suffixes, exec_only)
     Lisp_Object file, path, suffixes, exec_only;
{
  char *suff;

  if (STRINGP (path))
    path = decode_env_path (NULL, XSTRING (path)->data);

  if (EQ (suffixes, Qt))
    suff = EXEC_SUFFIXES;
  else if (NILP (suffixes))
    suff = "";
  else
    {
      if (!STRINGP (suffixes))
	{
	  struct gcpro gcpro1, gcpro2, gcpro3;
	  GCPRO3 (path, file, exec_only);	/* Is this necessary? */
	  suffixes = Fmapconcat (Qidentity, suffixes, build_string (":"));
	  UNGCPRO;
	}
      suff = XSTRING(suffixes)->data;
    }

  (void) openp (path, file, suff, &file, !NILP(exec_only));
  return file;
}

-- 
Hallvard