core: move loadNumpyArray to the lib

no need to compile it again

include/eigenpy/details.hpp

@@ -10,7 +10,6 @@
 #include "eigenpy/fwd.hpp"
 
 #include <patchlevel.h> // For PY_MAJOR_VERSION
-#include <numpy/arrayobject.h>
 #include <iostream>
 
 #include "eigenpy/eigenpy.hpp"
@@ -543,8 +542,6 @@ namespace eigenpy
     }
   };
   
-#define numpy_import_array() {if (_import_array() < 0) {PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import"); } }
-  
   template<typename MatType,typename EigenEquivalentType>
   void enableEigenPySpecific()
   {
@@ -581,7 +578,7 @@ namespace eigenpy
   template<typename MatType>
   void enableEigenPySpecific()
   {
-    numpy_import_array();
+    loadNumpyArray();
     if(check_registration<MatType>()) return;
     
     bp::to_python_converter<MatType,EigenToPy<MatType> >();

include/eigenpy/eigenpy.hpp

@@ -26,6 +26,10 @@
 
 namespace eigenpy
 {
+
+  /* Load numpy through Python */
+  void loadNumpyArray();
+
   /* Enable Eigen-Numpy serialization for a set of standard MatrixBase instance. */
   void EIGENPY_EXPORT enableEigenPy();
 

src/eigenpy.cpp

@@ -5,9 +5,24 @@
 
 #include "eigenpy/eigenpy.hpp"
 
+#include <numpy/arrayobject.h>
+
 namespace eigenpy
 {
 
+  void loadNumpyArray()
+  {
+    static bool loaded = false;
+    if(loaded) return;
+    
+    if(_import_array() < 0)
+    {
+      PyErr_Print(); PyErr_SetString(PyExc_ImportError, "numpy.core.multiarray failed to import");
+    }
+    else
+      loaded = true;
+  }
+
   /* Enable Eigen-Numpy serialization for a set of standard MatrixBase instances. */
   void enableEigenPy()
   {