Made tutorial more robust in terms of checking to see if the examples are...

Made tutorial more robust in terms of checking to see if the examples are installed. Also fixed a bug that appeared due to recent changes in structured text.

lib/python/Products/ZopeTutorial/TutorialTopic.py

@@ -107,6 +107,28 @@ class TutorialTopic(TextTopic):
         
     index_html=DTMLFile('dtml/lessonView', globals())
 
+    def checkInstallation(self, REQUEST):
+        """
+        Returns false if the tutorial examples are not correctly
+        installed. Also sets the 'hide_next' variable in the request
+        if the examples are not installed.
+        """
+        ok=0
+        if REQUEST.has_key('tutorialExamplesURL'):
+            url=REQUEST['tutorialExamplesURL']
+            base=REQUEST['BASE1']
+            if string.index(url, base) == 0:
+                url=url[len(base):]
+                try:
+                    self.getPhysicalRoot().unrestrictedTraverse(url)
+                    ok=1
+                except:
+                    pass
+
+        if not ok:
+            REQUEST.set('hide_next', 1)
+        return ok
+            
     def lessonURL(self, id, REQUEST):
         """
         URL of the examples for a lesson
@@ -121,7 +143,8 @@ class TutorialTopic(TextTopic):
         Navigate management frame to a given lesson's screen.
         """
         url=self.lessonURL(id, REQUEST)
-        if not url:
+        if not url or not self.checkInstallation(REQUEST):
+            REQUEST.set('hide_next', 0)
             return """\
 <p class="warning">
 Zope cannot find the tutorial examples.

lib/python/Products/ZopeTutorial/tutorial.stx

@@ -22,8 +22,7 @@ Welcome to the Zope Tutorial
   object you created in the Zope management screen, and viewing
   its "README" document.
   
-  <dtml-unless tutorialExamplesURL>
-  <dtml-call "REQUEST.set('hide_'+'next', 1)">
+  <dtml-unless expr="checkInstallation(REQUEST)">
   
   Install Tutorial Examples