[std-map] fix for non-default constructible types

Author: ManifoldFR

include/eigenpy/std-map.hpp

@@ -159,6 +159,45 @@ struct dict_to_map {
   }
 };
 
+/// Policies which handle the non-default constructible case
+/// and set_item() using emplace().
+template <class Container, bool NoProxy>
+struct emplace_set_derived_policies
+    : bp::map_indexing_suite<
+          Container, NoProxy,
+          emplace_set_derived_policies<Container, NoProxy> > {
+  typedef typename Container::key_type index_type;
+  typedef typename Container::value_type::second_type data_type;
+  typedef typename Container::value_type value_type;
+  using DerivedPolicies =
+      bp::detail::final_map_derived_policies<Container, NoProxy>;
+
+  template <class Class>
+  static void extension_def(Class& cl) {
+    //  Wrap the map's element (value_type)
+    std::string elem_name = "map_indexing_suite_";
+    bp::object class_name(cl.attr("__name__"));
+    bp::extract<std::string> class_name_extractor(class_name);
+    elem_name += class_name_extractor();
+    elem_name += "_entry";
+    namespace mpl = boost::mpl;
+
+    typedef typename mpl::if_<
+        mpl::and_<boost::is_class<data_type>, mpl::bool_<!NoProxy> >,
+        bp::return_internal_reference<>, bp::default_call_policies>::type
+        get_data_return_policy;
+
+    bp::class_<value_type>(elem_name.c_str(), bp::no_init)
+        .def("__repr__", &DerivedPolicies::print_elem)
+        .def("data", &DerivedPolicies::get_data, get_data_return_policy())
+        .def("key", &DerivedPolicies::get_key);
+  }
+
+  static void set_item(Container& container, index_type i, data_type const& v) {
+    container.emplace(i, v);
+  }
+};
+
 /**
  * @brief Expose the map-like container, e.g. (std::map).
  *
@@ -167,8 +206,9 @@ struct dict_to_map {
  * returned to Python.
  */
 template <class Container, bool NoProxy = false>
-struct GenericMapVisitor : public bp::map_indexing_suite<Container, NoProxy>,
-                           public dict_to_map<Container> {
+struct GenericMapVisitor
+    : public emplace_set_derived_policies<Container, NoProxy>,
+      public dict_to_map<Container> {
   typedef dict_to_map<Container> FromPythonDictConverter;
 
   static void expose(const std::string& class_name,

unittest/std_map.cpp

@@ -28,6 +28,12 @@ boost::unordered_map<std::string, T1> copy_boost(
   return obj;
 }
 
+struct X {
+  X() = delete;
+  X(int x) : val(x) {}
+  int val;
+};
+
 BOOST_PYTHON_MODULE(std_map) {
   eigenpy::enableEigenPy();
 
@@ -39,6 +45,8 @@ BOOST_PYTHON_MODULE(std_map) {
   eigenpy::GenericMapVisitor<boost::unordered_map<std::string, int> >::expose(
       "boost_map_int");
 
+  eigenpy::GenericMapVisitor<std::map<std::string, X> >::expose("StdMap_X");
+
   bp::def("std_map_to_dict", std_map_to_dict<double>);
   bp::def("copy", copy<double>);
   bp::def("copy_boost", copy_boost<int>);