Return interface objects when iterating over interface collections

danabr · lostmsu · commit 6d59aea0e4b8 · 2020-10-12T12:10:03.000-07:00
diff --git a/src/runtime/classbase.cs b/src/runtime/classbase.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
@@ -184,7 +185,6 @@ public static IntPtr tp_iter(IntPtr ob)
 
             var e = co.inst as IEnumerable;
             IEnumerator o;
-
             if (e != null)
             {
                 o = e.GetEnumerator();
@@ -199,7 +199,22 @@ public static IntPtr tp_iter(IntPtr ob)
                 }
             }
 
-            return new Iterator(o).pyHandle;
+            var elemType = typeof(object);
+            var iterType = co.inst.GetType();
+            foreach(var ifc in iterType.GetInterfaces())
+            {
+                if (ifc.IsGenericType)
+                {
+                    var genTypeDef = ifc.GetGenericTypeDefinition();
+                    if (genTypeDef == typeof(IEnumerable<>) || genTypeDef == typeof(IEnumerator<>))
+                    {
+                        elemType = ifc.GetGenericArguments()[0];
+                        break;
+                    }
+                }
+            }
+
+            return new Iterator(o, elemType).pyHandle;
         }
 
 
diff --git a/src/runtime/iterator.cs b/src/runtime/iterator.cs
@@ -10,10 +10,12 @@ namespace Python.Runtime
     internal class Iterator : ExtensionType
     {
         private IEnumerator iter;
+        private Type elemType;
 
-        public Iterator(IEnumerator e)
+        public Iterator(IEnumerator e, Type elemType)
         {
             iter = e;
+            this.elemType = elemType;
         }
 
 
@@ -41,7 +43,7 @@ public static IntPtr tp_iternext(IntPtr ob)
                 return IntPtr.Zero;
             }
             object item = self.iter.Current;
-            return Converter.ToPythonImplicit(item);
+            return Converter.ToPython(item, self.elemType);
         }
 
         public static IntPtr tp_iter(IntPtr ob)
diff --git a/src/tests/test_interface.py b/src/tests/test_interface.py
@@ -120,3 +120,19 @@ def test_implementation_access():
     assert 100 == i.__implementation__
     assert clrVal == i.__raw_implementation__
     assert i.__implementation__ != i.__raw_implementation__
+
+
+def test_interface_collection_iteration():
+    """Test interface type is used when iterating over interface collection"""
+    import System
+    from System.Collections.Generic import List
+    elem = System.IComparable(System.Int32(100))
+    typed_list = List[System.IComparable]()
+    typed_list.Add(elem)
+    for e in typed_list:
+        assert type(e).__name__ == "IComparable"
+
+    untyped_list = System.Collections.ArrayList()
+    untyped_list.Add(elem)
+    for e in untyped_list:
+        assert type(e).__name__ == "int"

Original file line number	Diff line number	Diff line change
`@@ -10,10 +10,12 @@ namespace Python.Runtime`
`10`	`10`	`internal class Iterator : ExtensionType`
`11`	`11`	`{`
`12`	`12`	`private IEnumerator iter;`
	`13`	`+ private Type elemType;`
`13`	`14`
`14`		`- public Iterator(IEnumerator e)`
	`15`	`+ public Iterator(IEnumerator e, Type elemType)`
`15`	`16`	`{`
`16`	`17`	`iter = e;`
	`18`	`+ this.elemType = elemType;`
`17`	`19`	`}`
`18`	`20`
`19`	`21`
`@@ -41,7 +43,7 @@ public static IntPtr tp_iternext(IntPtr ob)`
`41`	`43`	`return IntPtr.Zero;`
`42`	`44`	`}`
`43`	`45`	`object item = self.iter.Current;`
`44`		`- return Converter.ToPythonImplicit(item);`
	`46`	`+ return Converter.ToPython(item, self.elemType);`
`45`	`47`	`}`
`46`	`48`
`47`	`49`	`public static IntPtr tp_iter(IntPtr ob)`