From 7a55341e3202ad2aac6a1f8521e7b2794c639f7d Mon Sep 17 00:00:00 2001
From: Varun Agrawal <varagrawal@gmail.com>
Date: Tue, 26 Jul 2022 07:21:05 -0400
Subject: [PATCH] add IsGaussian template check

---
 gtsam/hybrid/HybridGaussianFactorGraph.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gtsam/hybrid/HybridGaussianFactorGraph.h b/gtsam/hybrid/HybridGaussianFactorGraph.h
index b98654b92..ca9d8049e 100644
--- a/gtsam/hybrid/HybridGaussianFactorGraph.h
+++ b/gtsam/hybrid/HybridGaussianFactorGraph.h
@@ -75,8 +75,14 @@ struct EliminationTraits<HybridGaussianFactorGraph> {
  * Everything inside needs to be hybrid factor or hybrid conditional.
  */
 class GTSAM_EXPORT HybridGaussianFactorGraph
-    : public HybridFactorGraph,,
+    : public HybridFactorGraph,
       public EliminateableFactorGraph<HybridGaussianFactorGraph> {
+ protected:
+  /// Check if FACTOR type is derived from GaussianFactor.
+  template <typename FACTOR>
+  using IsGaussian = typename std::enable_if<
+      std::is_base_of<GaussianFactor, FACTOR>::value>::type;
+
  public:
   using Base = HybridFactorGraph;
   using This = HybridGaussianFactorGraph;  ///< this class