Re: Semantics of autoload cookies on defcustoms

[Stefan Monnier]

>> Perhaps a good way to implement that is to write another argument into
>> the custom-autoload call.  That optional argument, if non-nil, would
>> specify this new combination of behaviors that I called #3.
>> The decision could be based on the presence of :set.

> Well, there's no need for an extra arg: we just then skip the
> custom-autoload and that should be all there is to it.

> How 'bout the patch below?
> What it does is the following:
> 1 - remove the minor-mode stuff which is unnecessary anyway (since the
>     custom-autoload line added just above already ensures that the package
>     gets loaded (which adds the setter) before the variable is custom-set).
> 2 - only add the custom-autoload line for those defcustom that have a setter
>     since it seems to be the only ones that need it.

> I guess this isn't quite right tho: the var should still cause autoloading
> if we want customize it (since it needs to go fetch the :type at the very
> least).  Is that what you meant by an additional arg to custom-autoload?

Here is a patch which I believe does it better:

- Add an arg to custom-autoload to mean that the variable should only be
  autoloaded for operations other than just `set'.
- Use this arg in autoload.el so that `set' only autoloads those variables
  that use a setter function.
- change custom.el so as to obey this new autoload alternative.
- change cus-edit.el to deal with the fact that those variables that have
  an autoload cookie but that are not autoloaded (because they don't have
  a setter) are not mistakenly marked as "changed outside customize".

With this patch, my Emacs starts up noticeably faster.
Should I install it?  Could some custom-theme specialist sanity-check it?


        Stefan


Index: lisp/emacs-lisp/autoload.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/emacs-lisp/autoload.el,v
retrieving revision 1.116
diff -u -r1.116 autoload.el
--- lisp/emacs-lisp/autoload.el 13 Jul 2006 18:13:06 -0000      1.116
+++ lisp/emacs-lisp/autoload.el 13 Jul 2006 19:29:16 -0000
@@ -124,7 +124,10 @@
            )
        `(progn
           (defvar ,varname ,init ,doc)
-          (custom-autoload ',varname ,file))))
+          (custom-autoload ',varname ,file
+                            ,(condition-case nil
+                                 (null (cadr (memq :set form)))
+                               (error nil))))))
 
      ((eq car 'defgroup)
       ;; In Emacs this is normally handled separately by cus-dep.el, but for
Index: lisp/custom.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/custom.el,v
retrieving revision 1.127
diff -u -r1.127 custom.el
--- lisp/custom.el      13 May 2006 16:16:43 -0000      1.127
+++ lisp/custom.el      13 Jul 2006 19:29:16 -0000
@@ -558,9 +558,10 @@
     (unless (member load loads)
       (put symbol 'custom-loads (cons (purecopy load) loads)))))
 
-(defun custom-autoload (symbol load)
-  "Mark SYMBOL as autoloaded custom variable and add dependency LOAD."
-  (put symbol 'custom-autoload t)
+(defun custom-autoload (symbol load &optional noset)
+  "Mark SYMBOL as autoloaded custom variable and add dependency LOAD.
+If NOSET is non-nil, don't bother autoloading LOAD when setting the variable."
+  (put symbol 'custom-autoload (if noset 'noset t))
   (custom-add-load symbol load))
 
 ;; This test is also in the C code of `user-variable-p'.
@@ -827,9 +828,6 @@
            (if (and (eq prop 'theme-value)
                     (boundp symbol))
                (let ((sv (get symbol 'standard-value)))
-                 (when (and (null sv) (custom-variable-p symbol))
-                   (custom-load-symbol symbol)
-                   (setq sv (get symbol 'standard-value)))
                  (unless (and sv
                                (equal (eval (car sv)) (symbol-value symbol)))
                     (setq old (list (list 'changed (symbol-value symbol))))))
@@ -907,6 +904,10 @@
            (when requests
              (put symbol 'custom-requests requests)
              (mapc 'require requests))
+            (unless (or (get symbol 'standard-value)
+                        (memq (get symbol 'custom-autoload) '(nil noset)))
+              ;; This symbol needs to be autoloaded, even just for a `set'.
+              (custom-load-symbol symbol))
            (setq set (or (get symbol 'custom-set) 'custom-set-default))
            (put symbol 'saved-value (list value))
            (put symbol 'saved-variable-comment comment)
Index: lisp/cus-edit.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/cus-edit.el,v
retrieving revision 1.296
diff -u -r1.296 cus-edit.el
--- lisp/cus-edit.el    12 Jul 2006 15:56:33 -0000      1.296
+++ lisp/cus-edit.el    13 Jul 2006 19:29:16 -0000
@@ -2668,7 +2668,18 @@
                             (error nil))
                           (cond
                            ((eq (caar tmp) 'user) 'saved)
-                           ((eq (caar tmp) 'changed) 'changed)
+                           ((eq (caar tmp) 'changed)
+                             (if (condition-case nil
+                                     (and (null comment)
+                                          (equal value
+                                                 (eval
+                                                  (car (get symbol 
'standard-value)))))
+                                   (error nil))
+                                 ;; The value was originally set outside
+                                 ;; custom, but it was set to the standard
+                                 ;; value (probably an autoloaded defcustom).
+                                 'standard
+                               'changed))
                            (t 'themed))
                         'changed))
                      ((setq tmp (get symbol 'standard-value))