diff --git a/python/obitools3/dms/dms.pyx b/python/obitools3/dms/dms.pyx
index 7658c13..b5dd5df 100644
--- a/python/obitools3/dms/dms.pyx
+++ b/python/obitools3/dms/dms.pyx
@@ -27,6 +27,8 @@ from obitools3.utils cimport bytes2str, \
                              str2bytes, \
                              tobytes, \
                              tostr
+                             
+from .object cimport OBIObjectClosedInstance
           
 from pathlib import Path
                            
@@ -74,18 +76,6 @@ cdef class DMS(OBIObject):
 
         if self._pointer == NULL :
             raise Exception("Failed opening or creating an OBIDMS")
-
-    
-    def __dealloc__(self):
-        """
-        Destructor of the DMS instance.
-        
-        The destructor automatically call the `close` method and
-        therefore free all the associated memory.
-        """
-        
-        self.close()
-        self._pointer=NULL
         
     # name property getter
     @property
@@ -103,9 +93,13 @@ cdef class DMS(OBIObject):
         
         the `close` method is automatically called by the object destructor.
         """
+        cdef OBIDMS_p pointer = self._pointer
         
-        if self._pointer!=NULL:
-            if (obi_close_dms(self._pointer)) < 0 :
+        OBIObject.close(self)
+        self._pointer=NULL
+
+        if pointer!=NULL:
+            if (obi_close_dms(pointer)) < 0 :
                 raise Exception("Problem closing an OBIDMS")
         else:
             raise OBIObjectClosedInstance()
diff --git a/python/obitools3/dms/object.pxd b/python/obitools3/dms/object.pxd
index 50cbe6c..1ec2513 100644
--- a/python/obitools3/dms/object.pxd
+++ b/python/obitools3/dms/object.pxd
@@ -4,6 +4,7 @@ cdef class OBIObject:
     cdef dict _dependent_object
     
     cpdef register(self, OBIObject object)
+    cpdef unregister(self, OBIObject object)
     cpdef close(self)
     
 cdef class OBIObjectClosedInstance(Exception):
diff --git a/python/obitools3/dms/object.pyx b/python/obitools3/dms/object.pyx
index 43bd21c..f73fba7 100644
--- a/python/obitools3/dms/object.pyx
+++ b/python/obitools3/dms/object.pyx
@@ -5,12 +5,18 @@ cdef class OBIObject:
     cpdef register(self, OBIObject object):
         self._dependent_object[id(object)]=object
         
-    cpdef close(self):
+    cpdef unregister(self, OBIObject object):
+        del self._dependent_object[id(object)]
+
+    def close(self):
         cdef OBIObject object
+        cdef list toclose = list(self._dependent_object.values())
         
-        for object in self._dependent_object.values():
+        for object in toclose:
             object.close()
             
+        assert len(dependent_object.values)==0
+            
     def __init__(self):
         self._dependent_object={}
             
diff --git a/python/obitools3/dms/view/view.pxd b/python/obitools3/dms/view/view.pxd
index 6806e2a..8963744 100644
--- a/python/obitools3/dms/view/view.pxd
+++ b/python/obitools3/dms/view/view.pxd
@@ -3,13 +3,15 @@
 from ..capi.obiview cimport Obiview_p
 from ..capi.obitypes cimport index_t, \
                              obitype_t
-                          
+
+from ..object cimport OBIObject                          
 from ..dms cimport DMS
+
 from ..column.column cimport Column
 
 
 
-cdef class View:
+cdef class View(OBIObject):
     
     cdef DMS       _dms
     cdef Obiview_p _pointer
diff --git a/python/obitools3/dms/view/view.pyx b/python/obitools3/dms/view/view.pyx
index d1b6287..7715386 100644
--- a/python/obitools3/dms/view/view.pyx
+++ b/python/obitools3/dms/view/view.pyx
@@ -16,13 +16,17 @@ from .dms  cimport __OBIDMS_VIEW_CLASS__
 
 from obitools3.utils cimport tobytes, \
                              bytes2str
-                             
+   
+from ..object cimport OBIObjectClosedInstance
+                          
 
-cdef class View :
+cdef class View(OBIObject) :
 
         
     def __init__(self,dms,int __internalCall__):
         
+        OBIObject.__init__(self)
+        
         if __internalCall__!=987654:
             raise RuntimeError('OBIView constructor cannot be called directly')
         
@@ -55,6 +59,8 @@ cdef class View :
                                % (str(self.name),
                                   bytes2str(view_name_b))
                               )
+            
+        self._dms.register(view)
                                 
         return view
     
@@ -85,6 +91,8 @@ cdef class View :
             message = "Error : Cannot create view %s" % bytes2str(view_name_b)
             raise RuntimeError(message)
                 
+        dms.register(view)
+
         return view
         
     @staticmethod
@@ -101,16 +109,25 @@ cdef class View :
         if view._pointer == NULL :
             raise RuntimeError("Error : Cannot open view %s" % bytes2str(view_name_b))
         
+        dms.register(view)
+
         return view
         
     def close(self):
-        if (self._pointer != NULL): 
+        cdef Obiview_p pointer = self._pointer
+        
+        if (pointer != NULL): 
+            self._dms.unregister(self)
+            OBIObject.close(self)
+            
+            self._pointer = NULL
+            
             if obi_save_and_close_view(self._pointer) < 0 :
                 raise Exception("Problem closing view %s" % 
                                 bytes2str(self.name))
+        else:
+            raise OBIObjectClosedInstance()
 
-    def __dealloc__(self):
-        self.close()
         
     def __repr__(self) :
         cdef str s = "{name:s}\n{comments:s}\n{line_count:d} lines\n".format(name       = str(self.name),