Derive all PreconditionBlock* class virtually from Subscriptor. This allows also...

git-svn-id: https://svn.dealii.org/trunk@4839 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/lac/include/lac/precondition_block.h b/deal.II/lac/include/lac/precondition_block.h
index 74e82735f12fd0fcbb78a63ededb48290e828181..9be09e0af7954f892364f7e53c907dafcf9456c4 100644 (file)
--- a/deal.II/lac/include/lac/precondition_block.h
+++ b/deal.II/lac/include/lac/precondition_block.h
@@ -75,7 +75,7 @@ template <typename number> class Vector;
  * @author Ralf Hartmann, Guido Kanschat, 1999, 2000
  */
 template<typename number, typename inverse_type = number>
-class PreconditionBlock
+class PreconditionBlock : public virtual Subscriptor
 {
   public:
                                     /**
@@ -293,7 +293,7 @@ class PreconditionBlock
  * @author Ralf Hartmann, Guido Kanschat, 1999, 2000
  */
 template<typename number, typename inverse_type = number>
-class PreconditionBlockJacobi : public Subscriptor,
+class PreconditionBlockJacobi : public virtual Subscriptor,
                                private PreconditionBlock<number,inverse_type>
 {
   public:
@@ -354,7 +354,7 @@ class PreconditionBlockJacobi : public Subscriptor,
  * @author Ralf Hartmann, Guido Kanschat, 1999, 2000
  */
 template<typename number, typename inverse_type = number>
-class PreconditionBlockSOR : public  Subscriptor,
+class PreconditionBlockSOR : public virtual Subscriptor,
                             protected PreconditionBlock<number,inverse_type>
 {
   public:
@@ -417,7 +417,8 @@ class PreconditionBlockSOR : public  Subscriptor,
  * @author Ralf Hartmann, Guido Kanschat, 1999, 2000
  */
 template<typename number, typename inverse_type = number>
-class PreconditionBlockSSOR : private PreconditionBlockSOR<number,inverse_type>
+class PreconditionBlockSSOR : public virtual Subscriptor,
+                             private PreconditionBlockSOR<number,inverse_type>
 {
   public:
                                     /**