From 4a4de532dc3a539a075e6d648ce3129b13cc544f Mon Sep 17 00:00:00 2001
From: Ryan Curtin <ryan@ratml.org>
Date: Sat, 6 Mar 2021 17:56:00 -0500
Subject: [PATCH] Move initialization of static members into a cpp file.

---
 .../environment/CMakeLists.txt                |  1 +
 .../environment/env_type.cpp                  | 27 +++++++++++++++++++
 .../environment/env_type.hpp                  |  4 ---
 3 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 src/mlpack/methods/reinforcement_learning/environment/env_type.cpp

diff --git a/src/mlpack/methods/reinforcement_learning/environment/CMakeLists.txt b/src/mlpack/methods/reinforcement_learning/environment/CMakeLists.txt
index 04e5b8b2a8..f93995ab75 100644
--- a/src/mlpack/methods/reinforcement_learning/environment/CMakeLists.txt
+++ b/src/mlpack/methods/reinforcement_learning/environment/CMakeLists.txt
@@ -2,6 +2,7 @@
 # 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
diff --git a/src/mlpack/methods/reinforcement_learning/environment/env_type.cpp b/src/mlpack/methods/reinforcement_learning/environment/env_type.cpp
new file mode 100644
index 0000000000..d5363b5501
--- /dev/null
+++ b/src/mlpack/methods/reinforcement_learning/environment/env_type.cpp
@@ -0,0 +1,27 @@
+/**
+ * @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 ContinuousActionEnv::State::dimension = 0;
+size_t ContinuousActionEnv::Action::size = 0;
+
+} // namespace rl
+} // namespace mlpack
diff --git a/src/mlpack/methods/reinforcement_learning/environment/env_type.hpp b/src/mlpack/methods/reinforcement_learning/environment/env_type.hpp
index e8513e3bb9..4fcf797322 100644
--- a/src/mlpack/methods/reinforcement_learning/environment/env_type.hpp
+++ b/src/mlpack/methods/reinforcement_learning/environment/env_type.hpp
@@ -105,8 +105,6 @@ class DiscreteActionEnv
    */
   bool IsTerminal(const State& /* state */) const { return false; }
 };
-size_t DiscreteActionEnv::State::dimension = 0;
-size_t DiscreteActionEnv::Action::size = 0;
 
 /**
  * To use the dummy environment, one may start by specifying the state and
@@ -201,8 +199,6 @@ class ContinuousActionEnv
    */
   bool IsTerminal(const State& /* state */) const { return false; }
 };
-size_t ContinuousActionEnv::State::dimension = 0;
-size_t ContinuousActionEnv::Action::size = 0;
 
 } // namespace rl
 } // namespace mlpack