Re: Need help writing file-visiting macro

[Kevin Rodgers <ihs_4664@yahoo.com>]

Roy Smith wrote:
 > I'm working in a software development system which has classes defined
 > in foo.mdl files, with the corresponding implementation code in
 > foo_Impl.c files I want to write a macro or function which lets you
 > flip back and forth between the two.  If I'm looking at a .mdl file, I
 > want it to construct the corresponding _Impl.c filename and visit that
 > file.  Is that possible?

Of course.

(defun find-impl-file (&optional mdl-file)
   "When visiting a \".mdl\", visit the corresponding \"_Impl.c\" file."
   (interactive)
   (when (null mdl-file)
     (setq mdl-file buffer-file-name))
   (unless (and mdl-file (equal (file-name-extension mdl-file) "mdl"))
     (error "%s is not a \".mdl\" file" mdl-file))
   (find-file (concat (file-name-sans-extension mdl-file) "_Impl.c")))

-- 
Kevin Rodgers