Re: Suggestion: Let the help command load autoloaded functions etc

[Lennart Borgman (gmail)]

David Kastrup wrote:
> "Stephen J. Turnbull" <address@hidden> writes:
>
> > David Kastrup writes:
> >
> >  > But printing the full file path (not present in the autocookie) in the
> >  > arg list will absolutely not change anything with regard to how the
> >  > libraries are found.
> >
> > True, but it will remind me of which tree it's getting the library
> > from.
>
> The arg list is not the right place for such a reminder, I think.

And even more since this is about loading the library, not visiting it. 
It should load the same library as for example (require ...).

And I just realized that I made a mistake there. I did not use the file 
name actually given in the autoload. I use this now in the attached 
patch, with extension stripped.
Index: help-fns.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/help-fns.el,v
retrieving revision 1.122
diff -u -r1.122 help-fns.el
--- help-fns.el 6 Jun 2008 20:02:42 -0000       1.122
+++ help-fns.el 17 Jul 2008 10:35:53 -0000
@@ -104,7 +104,7 @@
    ((byte-code-function-p def) (aref def 0))
    ((eq (car-safe def) 'lambda) (nth 1 def))
    ((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
-    "[Arg list not available until function definition is loaded.]")
+    "[Show arg list and full help (loads library LIBNAME).]")
    (t t)))
 
 (defun help-make-usage (function arglist)
@@ -264,7 +264,7 @@
         (def (if (symbolp real-function)
                  (symbol-function real-function)
                function))
-        file-name string
+        file-name file-auto-noext string
         (beg (if (commandp def) "an interactive " "a "))
          (pt1 (with-current-buffer (help-buffer) (point))))
     (setq string
@@ -287,6 +287,7 @@
                 "a Lisp macro")
                ((eq (car-safe def) 'autoload)
                 (setq file-name (nth 1 def))
+                 (setq file-auto-noext (file-name-sans-extension file-name))
                 (format "%s autoloaded %s"
                         (if (commandp def) "an interactive" "an")
                         (if (eq (nth 4 def) 'keymap) "keymap"
@@ -417,7 +418,26 @@
                  (high (help-highlight-arguments use doc)))
             (let ((fill-begin (point)))
              (insert (car high) "\n")
-             (fill-region fill-begin (point)))
+             (fill-region fill-begin (point))
+              ;; Add load link for autoloaded functions.
+              (let ((here (point-marker))
+                    (load-marker
+                     (concat "\\(Show arg list and full help\\) "
+                             "(loads library \\(LIBNAME\\))\.")))
+                (goto-char fill-begin)
+                (save-match-data
+                  (when (re-search-forward load-marker here t)
+                    (make-text-button (match-beginning 1)
+                                      (match-end 1)
+                                      'action
+                                      `(lambda (btn) (interactive)
+                                         (load-library ,file-auto-noext)
+                                         (describe-function ',function)))
+                    (replace-match
+                     (file-name-sans-extension
+                      (file-name-nondirectory file-name))
+                     t t nil 2)))
+                (goto-char here)))
             (setq doc (cdr high))))
         (let* ((obsolete (and
                          ;; function might be a lambda construct.