Re: [PATCH] Desktop mode saves mark-ring too verbosely

[Kelly Dean]

Stefan Monnier wrote on 23 Nov 2013:
>> You can (add-to-list 'desktop-locals-to-save 'mark-ring) and it works, so
>> long as you have the fix for bug 13951 applied. But it's very verbose; for
>> each element of mark-ring for each buffer, it writes an entry like
>> (let ((mk (make-marker))) (add-hook 'desktop-delay-hook (list 'lambda '()
>> (list 'set-marker mk 123 '(get-buffer "init.el")))) mk)
[snip]
> Having special-case code to print&read some variables is not in itself
> a bad idea, but I think we should do it via a table mapping variables to
> ad-hoc massaging functions.

Ok. Updated patch attached below.

This is more complex than my original patch, but it does what you want (IIUC 
what you want).

--- emacs-24.4/lisp/desktop.el
+++ emacs-24.4/lisp/desktop.el
@@ -135,7 +135,7 @@
 (require 'cl-lib)
 (require 'frameset)
 
-(defvar desktop-file-version "206"
+(defvar desktop-file-version "208"
   "Version number of desktop file format.
 Written into the desktop file and used at desktop read to provide
 backward compatibility.")
@@ -628,6 +628,20 @@
   "When the desktop file was last modified to the knowledge of this Emacs.
 Used to detect desktop file conflicts.")
 
+(defvar desktop-var-serdes-funs
+  (list (list
+        'mark-ring
+        (lambda (mr)
+          (mapcar #'marker-position mr))
+        (lambda (bmr)
+          (mapcar (lambda (p)
+                    (set-marker (make-marker) p))
+                  bmr))))
+  "Table of serdes functions for variables.
+Each record is a list of form: (var serializer deserializer).
+These records can be freely reordered, deleted, or new ones added.
+However, for compatibility, don't modify the functions for existing records.")
+
 (defun desktop-owner (&optional dirname)
   "Return the PID of the Emacs process that owns the desktop file in DIRNAME.
 Return nil if no desktop file found or no Emacs process is using it.
@@ -779,7 +793,12 @@
                (push here ll))
               ((member local loclist)
                (push local ll)))))
-     ll)))
+     ll)
+   (mapcar (lambda (record)
+            (let ((var (car record)))
+              (list var
+                    (funcall (cadr record) (symbol-value var)))))
+          desktop-var-serdes-funs)))
 
 ;; ----------------------------------------------------------------------------
 (defun desktop--v2s (value)
@@ -1336,7 +1355,9 @@
      buffer-readonly
      buffer-misc
      &optional
-     buffer-locals)
+     buffer-locals
+     compacted-vars
+     &rest _unsupported)
 
   (let ((desktop-file-version      file-version)
        (desktop-buffer-file-name   buffer-filename)
@@ -1426,7 +1447,14 @@
                  (set (car this) (cdr this)))
              ;; An entry of the form `symbol'.
              (make-local-variable this)
-             (makunbound this))))))))
+             (makunbound this)))
+         (unless (< desktop-file-version 208) ; Don't misinterpret any old 
custom args
+           (dolist (record compacted-vars)
+             (let*
+                 ((var (car record))
+                  (deser-fun (cl-caddr (assq var desktop-var-serdes-funs))))
+               (if deser-fun (set var (funcall deser-fun (cadr record))))))))
+       result))))
 
 ;; ----------------------------------------------------------------------------
 ;; Backward compatibility -- update parameters to 205 standards.