Fixed pythonnet#296 Converter support for PyObject (pythonnet#297)

* Fixed pythonnet#296

* Added test for pythonnet#296

* removed windows line endings

* Fixed comment and removed \r from added source

Author: rmadsen-ks

src/runtime/converter.cs

@@ -126,6 +126,12 @@ internal static IntPtr ToPython<T>(T value)
 
         internal static IntPtr ToPython(Object value, Type type)
         {
+            if(value is PyObject)
+            {
+                IntPtr handle = ((PyObject)value).Handle;
+                Runtime.XIncref(handle);
+                return handle;
+            }
             IntPtr result = IntPtr.Zero;
 
             // Null always converts to None in Python.
@@ -265,6 +271,13 @@ internal static bool ToManaged(IntPtr value, Type type,
         internal static bool ToManagedValue(IntPtr value, Type obType,
             out Object result, bool setError)
         {
+            if (obType == typeof(PyObject))
+            {
+                Runtime.XIncref(value); // PyObject() assumes ownership
+                result = new PyObject(value);
+                return true;
+            }
+
             // Common case: if the Python value is a wrapped managed object
             // instance, just return the wrapped object.
             ManagedType mt = ManagedType.GetManagedObject(value);

src/runtime/pyobject.cs

@@ -127,6 +127,16 @@ protected virtual void Dispose(bool disposing)
             }
         }
 
+        public long RefCount
+        {
+            get
+            {
+                if(!disposed)
+                    return Runtime.Refcount(obj);
+                return -1;
+            }
+        }
+
         public void Dispose()
         {
             Dispose(true);

src/testing/callbacktest.cs

@@ -28,4 +28,18 @@ public string Call_simpleDefaultArg_WithEmptyArgs(string moduleName)
             }
         }
     }
+
+    //==========================================================================
+    // Tests calling from Python into C# and back into Python using a PyObject.
+    // SelfCallbackTest should be inherited by a Python class. 
+    // Used in test_class.py / testCallback
+    //==========================================================================
+    public class SelfCallbackTest
+    {
+        public void Callback(Runtime.PyObject self)
+        {
+            using (Runtime.Py.GIL())
+                ((dynamic)self).PyCallback(self);
+        }
+    }
 }

src/tests/test_class.py

@@ -250,6 +250,21 @@ def testComparisons(self):
         c2 = ClassTest()
         self.assertRaises(TypeError, lambda: c1 < c2)
 
+    def testSelfCallback(self):
+        """ Test calling back and forth between this and a c# baseclass."""
+        class CallbackUser(Test.SelfCallbackTest):
+            def DoCallback(self):
+                self.PyCallbackWasCalled = False
+                self.SameReference = False
+                return self.Callback(self)
+            def PyCallback(self, self2):
+                self.PyCallbackWasCalled = True
+                self.SameReference = self == self2
+                
+        testobj = CallbackUser()
+        testobj.DoCallback()
+        self.assertTrue(testobj.PyCallbackWasCalled)
+        self.assertTrue(testobj.SameReference)
 
 class ClassicClass:
     def kind(self):