refactor to add access control to already_existing access control routines in access.py

lms/djangoapps/courseware/access.py

@@ -114,6 +114,7 @@ def _has_access_course_desc(user, course, action):
     Valid actions:
 
     'load' -- load the courseware, see inside the course
+    'load_forum' -- can load and contribute to the forums (one access level for now)
     'enroll' -- enroll.  Checks for enrollment window,
                   ACCESS_REQUIRE_STAFF_FOR_COURSE,
     'see_exists' -- can see that the course exists.
@@ -128,6 +129,13 @@ def _has_access_course_desc(user, course, action):
         # delegate to generic descriptor check to check start dates
         return _has_access_descriptor(user, course, 'load')
 
+    def can_load_forum():
+        """
+        Can this user access the forums in this course?
+        """
+        return (CourseEnrollment.is_enrolled(request.user, course_id) or \
+            _has_staff_access_to_descriptor(user, course)
+
     def can_enroll():
         """
         First check if restriction of enrollment by login method is enabled, both
@@ -193,6 +201,7 @@ def _has_access_course_desc(user, course, action):
 
     checkers = {
         'load': can_load,
+        'load_forum': can_load_forum,
         'enroll': can_enroll,
         'see_exists': see_exists,
         'staff': lambda: _has_staff_access_to_descriptor(user, course),