trying to initialize env_type var in same header

src/mlpack/methods/reinforcement_learning/environment/CMakeLists.txt

@@ -2,7 +2,6 @@
 # Anything not in this list will not be compiled into mlpack.
 set(SOURCES
   env_type.hpp
-  env_type.cpp
   mountain_car.hpp
   cart_pole.hpp
   continuous_mountain_car.hpp

src/mlpack/methods/reinforcement_learning/environment/env_type.cpp

@@ -1,29 +0,0 @@
-/**
- * @file methods/reinforcement_learning/environment/env_type.cpp
- * @author Nishant Kumar
- *
- * This file defines the static variables used by the discrete and continuous
- * environments.
- *
- * mlpack is free software; you may redistribute it and/or modify it under the
- * terms of the 3-clause BSD license.  You should have received a copy of the
- * 3-clause BSD license along with mlpack.  If not, see
- * http://www.opensource.org/licenses/BSD-3-Clause for more information.
- */
-#include "env_type.hpp"
-
-namespace mlpack {
-namespace rl {
-
-// Instantiate static members.
-
-size_t DiscreteActionEnv::State::dimension = 0;
-size_t DiscreteActionEnv::Action::size = 0;
-size_t DiscreteActionEnv::rewardSize = 0;
-
-size_t ContinuousActionEnv::State::dimension = 0;
-size_t ContinuousActionEnv::Action::size = 0;
-size_t ContinuousActionEnv::rewardSize = 0;
-
-} // namespace rl
-} // namespace mlpack

src/mlpack/methods/reinforcement_learning/environment/env_type.hpp

@@ -206,6 +206,19 @@ class ContinuousActionEnv
   static size_t rewardSize;
 };
 
+#ifndef MLPACK_METHODS_RL_ENVIRONMENT_ENV_TYPE_VARIABLES
+#define MLPACK_METHODS_RL_ENVIRONMENT_ENV_TYPE_VARIABLES
+
+size_t DiscreteActionEnv::State::dimension = 0;
+size_t DiscreteActionEnv::Action::size = 0;
+size_t DiscreteActionEnv::rewardSize = 0;
+
+size_t ContinuousActionEnv::State::dimension = 0;
+size_t ContinuousActionEnv::Action::size = 0;
+size_t ContinuousActionEnv::rewardSize = 0;
+
+#endif
+
 } // namespace rl
 } // namespace mlpack