From 9a0f973e7175f4a0c9170203e4a53bdc4673521b Mon Sep 17 00:00:00 2001
From: dellaert <dellaert@cc.gatech.edu>
Date: Mon, 4 May 2015 10:11:02 -0700
Subject: [PATCH] forward declare traits and moved MakeOptionalJacobian here...

---
 gtsam/base/OptionalJacobian.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/gtsam/base/OptionalJacobian.h b/gtsam/base/OptionalJacobian.h
index a83333caa..9ab8bc598 100644
--- a/gtsam/base/OptionalJacobian.h
+++ b/gtsam/base/OptionalJacobian.h
@@ -168,5 +168,20 @@ public:
   Jacobian* operator->(){ return pointer_; }
 };
 
+// forward declate
+template <typename T> struct traits;
+
+/**
+ * @brief: meta-function to generate JacobianTA optional reference
+ * Used mainly by Expressions
+ * @param T return type
+ * @param A argument type
+ */
+template<class T, class A>
+struct MakeOptionalJacobian {
+  typedef OptionalJacobian<traits<T>::dimension,
+      traits<A>::dimension> type;
+};
+
 } // namespace gtsam