From 821a82195e6947a96a97df0f7928e0ba0f799247 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 4 Jan 2009 23:15:50 +0000
Subject: [PATCH] change 'help' to open the main doc page instead of the docs
 for 'help' itself

svn: r13004
---
 collects/help/help-utils.ss               | 10 +++++--
 collects/help/search.ss                   |  4 ++-
 collects/scheme/help.ss                   | 32 +++++++++++++----------
 collects/scribblings/reference/help.scrbl |  3 ++-
 4 files changed, 31 insertions(+), 18 deletions(-)

diff --git a/collects/help/help-utils.ss b/collects/help/help-utils.ss
index 8e69e454cb..0388c69432 100644
--- a/collects/help/help-utils.ss
+++ b/collects/help/help-utils.ss
@@ -14,7 +14,7 @@
          scheme/list
          "search.ss")
 
-(provide search-for find-help find-help/lib)
+(provide search-for find-help find-help/lib go-to-main-page)
 
 (define (search-for strs)
   (perform-search (apply string-append (add-between strs " "))))
@@ -64,9 +64,15 @@
               (printf "  ~a\n" (car libs)))
             (loop (cdr libs))))))))
 
+(define (report-sending-browser file)
+  (printf "Sending to web browser...\n  file: ~a\n" file))
+
+(define (go-to-main-page)
+  (send-main-page #:notify report-sending-browser))
+
 (define (go-to-tag xref t)
   (let-values ([(file anchor) (xref-tag->path+anchor xref t)])
-    (printf "Sending to web browser...\n  file: ~a\n" file)
+    (report-sending-browser file)
     (when anchor (printf "  anchor: ~a\n" anchor))
     (unless (send-url/file file #:fragment (and anchor (uri-encode anchor)))
       (error 'help "browser launch failed"))))
diff --git a/collects/help/search.ss b/collects/help/search.ss
index c7e15cbf61..b83c3c3db2 100644
--- a/collects/help/search.ss
+++ b/collects/help/search.ss
@@ -9,9 +9,11 @@
 ;; using javascript.
 
 (define (send-main-page #:sub [sub "index.html"]
-                        #:fragment [fragment #f] #:query [query #f])
+                        #:fragment [fragment #f] #:query [query #f]
+                        #:notify [notify void])
   (let* ([path (build-path (find-user-doc-dir) sub)]
          [path (if (file-exists? path) path (build-path (find-doc-dir) sub))])
+    (notify path)
     (send-url/file path #:fragment fragment #:query query)))
 
 ;; This is an example of changing this code to use the online manuals.
diff --git a/collects/scheme/help.ss b/collects/scheme/help.ss
index da6966a0c4..dba69b06e3 100644
--- a/collects/scheme/help.ss
+++ b/collects/scheme/help.ss
@@ -33,31 +33,34 @@
        (raise-syntax-error
         #f
         (string-append "expects a single identifer, a #:from clause, or a"
-                       " #:search clause; try just `help' for more information")
+                       " #:search clause; try `(help help)' for more information")
         stx)])))
 
 (define (open-help-start)
-  (find-help #'help))
+  (go-to-main-page))
 
 ;; Autoload utilities from help/help-utils; if it does not exists,
 ;; suggest using docs.plt-scheme.org.
 
 (define-namespace-anchor anchor)
 (define get-binding
-  (let ([ns #f] [utils #f])
+  (let ([ns #f])
     (lambda (sym)
       (unless ns
-        (set! ns (namespace-anchor->empty-namespace anchor))
-        (set! utils (resolved-module-path-name
-                     (module-path-index-resolve
-                      (module-path-index-join 'help/help-utils #f)))))
-      (parameterize ([current-namespace ns])
-        (if (file-exists? utils)
-          (dynamic-require utils sym)
-          (lambda _
-            (error 'help "documentation system unavailable; ~a\n~a"
-                   "try http://docs.plt-scheme.org/"
-                   (format "  (missing file: ~a)" utils))))))))
+        (set! ns (namespace-anchor->empty-namespace anchor)))
+      (with-handlers ([exn:fail?
+                       (lambda (exn)
+                         ((error-display-handler) 
+                          (if (exn? exn)
+                              (exn-message exn)
+                              (format "~s" exn))
+                          exn)
+                         (raise-user-error
+                          'help
+                          (string-append
+                           "documentation system unavailable; "
+                           "try http://docs.plt-scheme.org/")))])
+        (dynamic-require 'help/help-utils sym)))))
 
 (define-syntax-rule (define-help-autoload id)
   (define id
@@ -67,3 +70,4 @@
 (define-help-autoload find-help)
 (define-help-autoload find-help/lib)
 (define-help-autoload search-for)
+(define-help-autoload go-to-main-page)
diff --git a/collects/scribblings/reference/help.scrbl b/collects/scribblings/reference/help.scrbl
index 1d2b11a3fc..b98f6f070f 100644
--- a/collects/scribblings/reference/help.scrbl
+++ b/collects/scribblings/reference/help.scrbl
@@ -32,7 +32,8 @@ browser (using the user's selected browser) to display the results.
 @margin-note{See @schememodname[net/sendurl] for information on how
 the user's browser is launched to display help information.}
 
-A simple @scheme[help] or @scheme[(help)] form opens this page. 
+A simple @scheme[help] or @scheme[(help)] form opens the main
+documentation page.
 
 A @scheme[(help id)] form looks for documentation specific to the
 current binding of @scheme[id]. For example,