use the new OptionalRef to protect session shutdown

The original version was sensible to static initialisation order,
which shold be resolved now, because of OptionalLink's dtor
explicitly disabling any further access.

src/lib/element-tracker.hpp

@@ -41,8 +41,10 @@
  ** @warning AutoRegistered does not check accessibility of the configured
  ** registry, when detaching an element. Especially, when detaching in turn
  ** gets automatically invoked from some kind of cleanup, care has to be taken
- ** to ensure the registry is still available. Ignoring this might lead to
- ** segfault on application shutdown. ///TICKET #574
+ ** to ensure the registry is still available. The Functions
+ ** AutoRegistered::is_attached_to and AutoRegistered::deactivateRegistryLink
+ ** can be used for detaching an Registry explicitly before destruction.
+ ** Ignoring this might lead to segfault on application shutdown. /////////////////TICKET #574
  ** 
  ** @see session-element-tracker-test.cpp
  ** @see session-interface-modules.hpp
@@ -56,18 +58,15 @@
 #define LIB_ELEMENT_TRACKER_H
 
 #include "lib/p.hpp"
-#include "lib/wrapper.hpp"
+#include "lib/optional-ref.hpp"
 #include "lib/util-foreach.hpp"
 #include "lib/ref-array-impl.hpp"
 
-#include <tr1/functional>
-
 
 
 namespace lib {
   
   using lumiera::P;
-  using std::tr1::function;
   using util::isSameObject;
   
   /**
@@ -173,7 +172,7 @@ namespace lib {
     {
     public:
       typedef lib::ElementTracker<TAR> Registry;
-      typedef function<Registry&(void)> RegistryLink;
+      typedef lib::OptionalRef<Registry> RegistryLink;
       
       /** detach this element
        *  from the element-tracking registry.
@@ -210,31 +209,22 @@ namespace lib {
         }
       
       
-      template<typename FUN>
-      static void
-      establishRegistryLink (FUN link)
-        {
-          AutoRegistered::getRegistry = link;
-        }
-      
       static void
       setRegistryInstance (Registry& registry_to_use)
         {
-          RegistryLink accessInstance = wrapper::refFunction(registry_to_use);
-          establishRegistryLink (accessInstance);
+          getRegistry.link_to (registry_to_use);
         }
       
       static void
       deactivateRegistryLink()
         {
-          getRegistry = RegistryLink();  // empty accessor function
+          getRegistry.clear();
         }
       
       static bool
       is_attached_to (Registry const& someRegistry)
         {
-          return bool(getRegistry)
-              && isSameObject (someRegistry, getRegistry());
+          return getRegistry.points_to (someRegistry);
         }
       
     protected:

src/proc/asset/sequence.cpp

@@ -47,7 +47,7 @@ namespace asset {
     getRegistry().append (newSeq);
     
     ENSURE (newSeq);
-    ENSURE (getRegistry().isRegistered(*newSeq));
+    ENSURE (getRegistry().isRegistered (*newSeq));
     return newSeq;
   }
   

src/proc/asset/timeline.cpp

@@ -53,7 +53,7 @@ namespace asset {
     getRegistry().append (newElement);
     
     ENSURE (newElement);
-    ENSURE (getRegistry().isRegistered(*newElement));
+    ENSURE (getRegistry().isRegistered (*newElement));
     return newElement;
   }