[Python] Add function to expose constant variables in the current Python scope

bindings/python/CMakeLists.txt

@@ -44,6 +44,7 @@ ENDFOREACH(dep ${PKG_CONFIG_PYWRAP_REQUIRES})
 SET(${PYWRAP}_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/${PYTHON_SITELIB}/${PROJECT_NAME})
 
 SET(${PROJECT_NAME}_PYTHON_HEADERS
+  utils/constant.hpp
   utils/eigen_container.hpp
   utils/handler.hpp
   utils/copyable.hpp

bindings/python/utils/constant.hpp

+//
+// Copyright (c) 2018 CNRS
+//
+// This file is part of Pinocchio
+// Pinocchio is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation, either version
+// 3 of the License, or (at your option) any later version.
+//
+// Pinocchio is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Lesser Public License for more details. You should have
+// received a copy of the GNU Lesser General Public License along with
+// Pinocchio If not, see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef __se3_python_utils_constant_hpp__
+#define __se3_python_utils_constant_hpp__
+
+#include <boost/python/scope.hpp>
+
+namespace boost
+{
+  namespace python
+  {
+    
+    ///
+    /// \brief Define a constant given its value and a name within the current Boost Python scope.
+    ///
+    /// \tparam T Type of the constant.
+    ///
+    /// \param[in] name Name of the constant.
+    /// \param[in] value Value of the constant.
+    ///
+    template<typename T>
+    void def_constant(const char * name, const T & value)
+    {
+      namespace bp = boost::python;
+      bp::scope().attr(name) = value;
+    }
+    
+  } // namespace python
+} // namespace boost
+
+#endif // ifndef __se3_python_utils_constant_hpp__