1 files changed, 6 insertions, 1 deletions
diff --git a/odb/context.hxx b/odb/context.hxx
index 0af3b3c..805691f 100644
--- a/odb/context.hxx
+++ b/odb/context.hxx
@@ -1512,7 +1512,8 @@ protected:
     ~data () {}
 
     data (std::ostream& os)
-        : os_ (os.rdbuf ()),
+        : extra_ (0),
+          os_ (os.rdbuf ()),
           in_comment_ (false),
           top_object_ (0),
           cur_object_ (0),
@@ -1522,6 +1523,8 @@ protected:
     }
 
   public:
+    void* extra_;
+
     std::ostream os_;
     std::stack<std::streambuf*> os_stack_;
 
@@ -1551,6 +1554,8 @@ protected:
 public:
   typedef ::features features_type;
 
+  void*& extra; // Extra data that may need to be shared by a sub-system.
+
   std::ostream& os;
   semantics::unit& unit;
   options_type const& options;