1 files changed, 9 insertions, 0 deletions
diff --git a/core/opt_exception.hpp b/core/opt_exception.hpp
index 027f783..df9030a 100644
--- a/core/opt_exception.hpp
+++ b/core/opt_exception.hpp
@@ -143,6 +143,15 @@ namespace opt_utilities
     {}
   };
 
+  class data_unsetable
+    :public opt_exception
+  {
+  public:
+    data_unsetable()
+      :opt_exception("data unsetable")
+    {}
+  };
+
 }