return best representation of polymorphic types (fixes #105)

example/example.cpp

@@ -24,6 +24,7 @@ void init_ex12(py::module &);
 void init_ex13(py::module &);
 void init_ex14(py::module &);
 void init_ex15(py::module &);
+void init_ex16(py::module &);
 void init_issues(py::module &);
 
 PYBIND11_PLUGIN(example) {
@@ -44,6 +45,7 @@ PYBIND11_PLUGIN(example) {
     init_ex13(m);
     init_ex14(m);
     init_ex15(m);
+    init_ex16(m);
     init_issues(m);
 
     return m.ptr();

example/example16.cpp

@@ -0,0 +1,24 @@
+/*
+    example/example16.cpp -- automatic upcasting for polymorphic types
+
+    Copyright (c) 2015 Wenzel Jakob <wenzel@inf.ethz.ch>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#include "example.h"
+
+struct BaseClass { virtual ~BaseClass() {} };
+struct DerivedClass1 : BaseClass { };
+struct DerivedClass2 : BaseClass { };
+
+void init_ex16(py::module &m) {
+    py::class_<BaseClass>(m, "BaseClass").def(py::init<>());
+    py::class_<DerivedClass1>(m, "DerivedClass1").def(py::init<>());
+    py::class_<DerivedClass2>(m, "DerivedClass2").def(py::init<>());
+
+    m.def("return_class_1", []() -> BaseClass* { return new DerivedClass1(); });
+    m.def("return_class_2", []() -> BaseClass* { return new DerivedClass2(); });
+    m.def("return_none", []() -> BaseClass* { return nullptr; });
+}

example/example16.py

@@ -0,0 +1,12 @@
+from __future__ import print_function
+import sys
+
+sys.path.append('.')
+
+from example import return_class_1
+from example import return_class_2
+from example import return_none
+
+print(type(return_class_1()))
+print(type(return_class_2()))
+print(type(return_none()))

example/example16.ref

@@ -0,0 +1,3 @@
+<class 'example.DerivedClass1'>
+<class 'example.DerivedClass2'>
+<type 'NoneType'>