What's the right way to define a custom info path.

[pierre . techoueyres]

** The context
   - I'm working on Windows 7 (but I think the Windows version is not 
important) with Emacs 24.5.1.
   - My Emacs is installed on c:/programmes/emacs (c:/programmes is a custom 
directory, not the standard Program Files which contains spaces).
   - I installed some packages with package.el :
     - org-plus-contrib
     - ecb

   - I extracted some packages from git versions on ~/.emacs.d/site-lisp :
     - tramp
     - cedet

   All packages have info files.

** My attempts
   I tried to setup everything properly to have Info display the right version 
of all manuals :
   - tramp in c:/programmes/emacs/share/emacs/24.5.50/lisp/net/ is superseded 
by the one in ~/.emacs.d/site-lisp/emacs-tramp an the info manual retrieved is 
the right one.
   - cedet in ~/.emacs.d/site-lisp/cedet is loaded before the one in 
c:/programmes/emacs an so on for the info manual
   - packages cedet superseded the one in emacs-core and Info display the 
latest manual

** what I've in my init.el

   First I've disabled autoexec of package initialize with `(setq 
package-enable-at-startup nil)' (this is needed to allow loading of custom 
cedet).

   Then I've added tramp's install dir to my load-path.

   Then defined a custom-file to ~/.emacs.d/custom.el

   Then add to my load-path cedet install dir and load the cedet-devel-load 
file which initialize everything.

   Then call package-initialize, and *after* load my custom-file.

** My problems
   First I tried to setup the Info-path with the custom variable 
`Info-default-directory-list' but that doesn't work, because of 
package-activate-1 which call info-initialize so the customization of 
Info-default-directory-list is done too late. And worse it's not correctly 
initialized !!!


   Next I try using `Info-directory-list' but to do so I must require info and 
call info-initialize in my init.el and I prefer to avoid that.

   Then I looked at `Info-additional-directory-list' which has the same problem 
as `Info-default-directory-list'.

** What I think should be done.
   1) `Info-default-directory-list' should be correctly initialized for the 
emacs w32.
      1) To do that env.el should provide an `w32-substitute-env-vars' to allow 
replacement of %var% strings with the corresponding env vars.
      2) The defcustom of Info-default-directory-list should call 
(substitute-env-vars configure-info-directory) instead of 
configure-info-directory directly.      

   2) `package-activate-1' should not require info nor use `info-initialize'. 
Instead it should add info paths on `Info-default-directory-list' or 
`Info-additional-directory-list' (maybe the later).

** My questions
   Have I do something wrong with my config ? Should I set an INFOPATH env var 
with absolutes paths ?
   If the answer of the previous questions is : No, should I open bugs ?
   
   Sorry for the really long message and the poor english.

** Some patches
   #+BEGIN_SRC ediff
3 files changed, 46 insertions(+), 5 deletions(-)
lisp/emacs-lisp/package.el |  9 +++++----
lisp/info.el               |  2 +-
lisp/w32-fns.el            | 40 ++++++++++++++++++++++++++++++++++++++++

modified   lisp/emacs-lisp/package.el
@@ -690,10 +690,11 @@ package-activate-1
                       loaded-files-list))))
     ;; Add info node.
     (when (file-exists-p (expand-file-name "dir" pkg-dir))
-      ;; FIXME: not the friendliest, but simple.
-      (require 'info)
-      (info-initialize)
-      (push pkg-dir Info-directory-list))
+      (unless (member pkg-dir Info-default-directory-list)
+       (push pkg-dir Info-default-directory-list))
+      (when (and (bound-and-true-p Info-directory-list)
+                (not (member pkg-dir Info-directory-list)))
+       (push pkg-dir Info-directory-list)))
     (push name package-activated-list)
     ;; Don't return nil.
     t))
modified   lisp/info.el
@@ -186,7 +186,7 @@ Info-default-directory-list
           (or (and (featurep 'ns)
                    (let ((dir (expand-file-name "../info" data-directory)))
                      (if (file-directory-p dir) dir)))
-              configure-info-directory)))
+              (substitute-env-vars configure-info-directory))))
         (prefixes
          ;; Directory trees in which to look for info subdirectories
          (prune-directory-list '("/usr/local/" "/usr/" "/opt/" "/")))
modified   lisp/w32-fns.el
@@ -340,4 +340,44 @@ w32-append-code-lines
   (delete-matching-lines "^$\\|^;")
   (save-buffers-kill-emacs t))
 
+
+;;;; Support for environment variables
+(defconst w32-env--substitute-vars-regexp
+  "%\\(?:\\(?1:[[:alnum:]_\-]+\\)%\\|%\\)")
+
+(defun w32-substitute-env-vars (string &optional when-undefined)
+  "Substitute environment variables referred to in STRING.
+`%FOO%' where FOO is an environment variable name means to substitute
+the value of that variable.  The variable name should be terminated
+with a character not a letter, digit or underscore; otherwise, enclose
+the entire variable name in braces.  For instance, in `ab%cd-x%',
+`%cd-x%' is treated as an environment variable.
+
+If WHEN-DEFINED is nil, references to undefined environment variables
+are replaced by the empty string; if it is a function, the function is called
+with the variable name as argument and should return the text with which
+to replace it or nil to leave it unchanged.
+If it is non-nil and not a function, references to undefined variables are
+left unchanged.
+
+Use `%%' to insert a single percent sign."
+  (let ((start 0))
+    (while (string-match w32-env--substitute-vars-regexp string start)
+      (cond ((match-beginning 1)
+            (let* ((var (match-string 1 string))
+                    (value (getenv var)))
+               (if (and (null value)
+                        (if (functionp when-undefined)
+                            (null (setq value (funcall when-undefined var)))
+                          when-undefined))
+                   (setq start (match-end 0))
+                 (setq string (replace-match (or value "") t t string)
+                       start (+ (match-beginning 0) (length value))))))
+           (t
+            (setq string (replace-match "%" t t string)
+                  start (+ (match-beginning 0) 1)))))
+    string))
+
+(defalias 'substitute-env-vars 'w32-substitute-env-vars))
+
 ;;; w32-fns.el ends here
   #+END_SRC