Merge pull request pythonnet#65 from medicomp/struct-default-constructor

tonyroberts · tonyroberts · commit 80fcbc4cdf31 · 2015-02-02T10:02:38.000Z
Struct default constructor
diff --git a/src/runtime/classobject.cs b/src/runtime/classobject.cs
@@ -26,7 +26,7 @@ internal class ClassObject : ClassBase {
 
         internal ClassObject(Type tp) : base(tp) {
             ctors = type.GetConstructors();
-            binder = new ConstructorBinder();
+            binder = new ConstructorBinder(type);
 
             for (int i = 0; i < ctors.Length; i++) {
                 binder.AddMethod(ctors[i]);
diff --git a/src/runtime/constructorbinder.cs b/src/runtime/constructorbinder.cs
@@ -21,8 +21,11 @@ namespace Python.Runtime {
     //========================================================================
 
     internal class ConstructorBinder : MethodBinder {
+        private Type _containingType = null;
 
-        internal ConstructorBinder () : base() {}
+        internal ConstructorBinder(Type containingType) : base() {
+            _containingType = containingType;
+        }
 
         //====================================================================
         // Constructors get invoked when an instance of a wrapped managed
@@ -53,9 +56,31 @@ internal object InvokeRaw(IntPtr inst, IntPtr args, IntPtr kw) {
         /// </remarks>
         internal object InvokeRaw(IntPtr inst, IntPtr args, IntPtr kw,
                                   MethodBase info) {
-            Binding binding = this.Bind(inst, args, kw, info);
             Object result;
 
+            if (_containingType.IsValueType && !_containingType.IsPrimitive && 
+                !_containingType.IsEnum && _containingType != typeof (decimal) && 
+                Runtime.PyTuple_Size(args) == 0) {
+                // If you are trying to construct an instance of a struct by
+                // calling its default constructor, that ConstructorInfo
+                // instance will not appear in reflection and the object must 
+                // instead be constructed via a call to 
+                // Activator.CreateInstance().
+                try {
+                    result = Activator.CreateInstance(_containingType);
+                }
+                catch (Exception e) {
+                    if (e.InnerException != null) {
+                        e = e.InnerException;
+                    }
+                    Exceptions.SetError(e);
+                    return null;
+                }
+                return result;
+            }
+
+            Binding binding = this.Bind(inst, args, kw, info);
+
             if (binding == null) {
                 // It is possible for __new__ to be invoked on construction
                 // of a Python subclass of a managed class, so args may
diff --git a/src/tests/test_class.py b/src/tests/test_class.py
@@ -130,10 +130,9 @@ def testStructConstruction(self):
         """Test construction of structs."""
         from System.Drawing import Point
 
-        def test():
-            p = Point()
-
-        self.assertRaises(TypeError, test)
+        p = Point()
+        self.assertTrue(p.X == 0)
+        self.assertTrue(p.Y == 0)
 
         p = Point(0, 0)
         self.assertTrue(p.X == 0)
