completed implicit type casters for reference_wrapper

docs/changelog.rst

@@ -16,6 +16,7 @@ Changelog
 * Added a ``get_include()`` function to the Python module that returns the path
   of the directory containing the installed pybind11 header files
 * Documentation improvements: import issues, symbol visibility, pickling, limitations
+* Added casting support for ``std::reference_wrapper<>``
 
 1.4 (April 7, 2016)
 --------------------------

example/issues.cpp

@@ -20,7 +20,7 @@ struct DispatchIssue : Base {
     }
 };
 
-struct Placeholder { int i; };
+struct Placeholder { int i; Placeholder(int i) : i(i) { } };
 
 void dispatch_issue_go(const Base * b) { b->dispatch(); }
 
@@ -42,17 +42,19 @@ void init_issues(py::module &m) {
     m2.def("dispatch_issue_go", &dispatch_issue_go);
 
     py::class_<Placeholder>(m2, "Placeholder")
+        .def(py::init<int>())
         .def("__repr__", [](const Placeholder &p) { return "Placeholder[" + std::to_string(p.i) + "]"; });
 
     // #171: Can't return reference wrappers (or STL datastructures containing them)
-    m2.def("return_vec_of_reference_wrapper", [] {
+    m2.def("return_vec_of_reference_wrapper", [](std::reference_wrapper<Placeholder> p4){
         Placeholder *p1 = new Placeholder{1};
         Placeholder *p2 = new Placeholder{2};
-        Placeholder *p3 = new Placeholder{2};
+        Placeholder *p3 = new Placeholder{3};
         std::vector<std::reference_wrapper<Placeholder>> v;
         v.push_back(std::ref(*p1));
         v.push_back(std::ref(*p2));
         v.push_back(std::ref(*p3));
+        v.push_back(p4);
         return v;
     });
 }

example/issues.py

@@ -5,7 +5,7 @@ sys.path.append('.')
 
 from example.issues import print_cchar, print_char
 from example.issues import DispatchIssue, dispatch_issue_go
-from example.issues import return_vec_of_reference_wrapper
+from example.issues import Placeholder ,return_vec_of_reference_wrapper
 
 print_cchar("const char *")
 print_char('c')
@@ -28,4 +28,4 @@ class PyClass2(DispatchIssue):
 b = PyClass2()
 dispatch_issue_go(b)
 
-print(return_vec_of_reference_wrapper())
+print(return_vec_of_reference_wrapper(Placeholder(4)))

example/issues.ref

@@ -2,4 +2,4 @@ const char *
 c
 Failed as expected: Tried to call pure virtual function "dispatch"
 Yay..
-[Placeholder[1], Placeholder[2], Placeholder[2]]
+[Placeholder[1], Placeholder[2], Placeholder[3], Placeholder[4]]

include/pybind11/cast.h

@@ -246,6 +246,8 @@ public:
     static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
         return type_caster<type>::cast(&src.get(), policy, parent);
     }
+    template <typename T> using cast_op_type = std::reference_wrapper<type>;
+    operator std::reference_wrapper<type>() { return std::ref(*((type *) this->value)); }
 };
 
 #define PYBIND11_TYPE_CASTER(type, py_name) \