Merge pull request #37 from QuantConnect/bug-pylist-to-csharplist-round-conversion

PyList to C# List round trip conversion

Author: jaredbroad

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.0.5.25
+current_version = 1.0.5.26
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(\.(?P<release>[a-z]+)(?P<dev>\d+))?
 serialize = 
 	{major}.{minor}.{patch}.{release}{dev}

conda.recipe/meta.yaml

@@ -1,6 +1,6 @@
 package:
   name: pythonnet
-  version: "1.0.5.25"
+  version: "1.0.5.26"
 
 build:
   skip: True  # [not win]

setup.py

@@ -485,7 +485,7 @@ def run(self):
 
 setup(
     name="pythonnet",
-    version="1.0.5.25",
+    version="1.0.5.26",
     description=".Net and Mono integration for Python",
     url='https://pythonnet.github.io/',
     license='MIT',

src/SharedAssemblyInfo.cs

@@ -25,4 +25,4 @@
 // Version Information. Keeping it simple. May need to revisit for Nuget
 // See: https://codingforsmarties.wordpress.com/2016/01/21/how-to-version-assemblies-destined-for-nuget/
 // AssemblyVersion can only be numeric
-[assembly: AssemblyVersion("1.0.5.25")]
+[assembly: AssemblyVersion("1.0.5.26")]

src/clrmodule/ClrModule.cs

@@ -53,7 +53,7 @@ public static void initclr()
         {
 #if USE_PYTHON_RUNTIME_VERSION
             // Has no effect until SNK works. Keep updated anyways.
-            Version = new Version("1.0.5.25"),
+            Version = new Version("1.0.5.26"),
 #endif
             CultureInfo = CultureInfo.InvariantCulture
         };

src/embed_tests/TestConverter.cs

@@ -1,4 +1,6 @@
-using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
 using Python.Runtime;
 
 namespace Python.EmbeddingTest
@@ -17,6 +19,30 @@ public void Dispose()
             PythonEngine.Shutdown();
         }
 
+        [Test]
+        public void ConvertListRoundTrip()
+        {
+            var list = new List<Type> { typeof(decimal), typeof(int) };
+            var py = list.ToPython();
+            object result;
+            var converted = Converter.ToManaged(py.Handle, typeof(List<Type>), out result, false);
+
+            Assert.IsTrue(converted);
+            Assert.AreEqual(result, list);
+        }
+
+        [Test]
+        public void ConvertPyListToArray()
+        {
+            var array = new List<Type> { typeof(decimal), typeof(int) };
+            var py = array.ToPython();
+            object result;
+            var converted = Converter.ToManaged(py.Handle, typeof(Type[]), out result, false);
+
+            Assert.IsTrue(converted);
+            Assert.AreEqual(result, array);
+        }
+
         [Test]
         public void TestConvertSingleToManaged(
             [Values(float.PositiveInfinity, float.NegativeInfinity, float.MinValue, float.MaxValue, float.NaN,

src/runtime/converter.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections;
+using System.Collections.Generic;
 using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Security;
@@ -166,19 +167,20 @@ internal static IntPtr ToPython(object value, Type type)
                 return result;
             }
 
-            if (value is IList && value.GetType().IsGenericType)
+            var list = value as IList;
+            if (list != null && value.GetType().IsGenericType)
             {
-                using (var resultlist = new PyList())
+                using (var resultList = new PyList())
                 {
-                    foreach (object o in (IEnumerable)value)
+                    for (var i = 0; i < list.Count; i++)
                     {
-                        using (var p = new PyObject(ToPython(o, o?.GetType())))
+                        using (var p = list[i].ToPython())
                         {
-                            resultlist.Append(p);
+                            resultList.Append(p);
                         }
                     }
-                    Runtime.XIncref(resultlist.Handle);
-                    return resultlist.Handle;
+                    Runtime.XIncref(resultList.Handle);
+                    return resultList.Handle;
                 }
             }
 
@@ -382,6 +384,15 @@ internal static bool ToManagedValue(IntPtr value, Type obType,
                 return true;
             }
 
+            if(obType.IsGenericType && Runtime.PyObject_TYPE(value) == Runtime.PyListType)
+            {
+                var typeDefinition = obType.GetGenericTypeDefinition();
+                if (typeDefinition == typeof(List<>))
+                {
+                    return ToList(value, obType, out result, setError);
+                }
+            }
+
             // Common case: if the Python value is a wrapped managed object
             // instance, just return the wrapped object.
             ManagedType mt = ManagedType.GetManagedObject(value);
@@ -1003,7 +1014,6 @@ private static void SetConversionError(IntPtr value, Type target)
             Exceptions.SetError(Exceptions.TypeError, $"Cannot convert {src} to {target}");
         }
 
-
         /// <summary>
         /// Convert a Python value to a correctly typed managed array instance.
         /// The Python value must support the Python sequence protocol and the
@@ -1015,7 +1025,7 @@ private static bool ToArray(IntPtr value, Type obType, out object result, bool s
             int size = Runtime.PySequence_Size(value);
             result = null;
 
-            if (size < 0 || elementType.IsGenericType)
+            if (elementType.IsGenericType)
             {
                 if (setError)
                 {
@@ -1026,7 +1036,49 @@ private static bool ToArray(IntPtr value, Type obType, out object result, bool s
 
             Array items = Array.CreateInstance(elementType, size);
 
-            // XXX - is there a better way to unwrap this if it is a real array?
+            var index = 0;
+            result = items;
+            return ApplyActionToPySequence(value, obType, setError, size, elementType, o =>
+            {
+                items.SetValue(o, index++);
+            });
+        }
+
+        /// <summary>
+        /// Convert a Python value to a correctly typed managed list instance.
+        /// The Python value must support the Python sequence protocol and the
+        /// items in the sequence must be convertible to the target list type.
+        /// </summary>
+        private static bool ToList(IntPtr value, Type obType, out object result, bool setError)
+        {
+            var elementType = obType.GetGenericArguments()[0];
+            var size = Runtime.PySequence_Size(value);
+
+            result = Activator.CreateInstance(obType, args: size);
+            var resultList = (IList)result;
+            return ApplyActionToPySequence(value, obType, setError, size, elementType, o => resultList.Add(o));
+        }
+
+        /// <summary>
+        /// Helper method that will enumerate a Python sequence convert its values to the given
+        /// type and send them to the provided action
+        /// </summary>
+        private static bool ApplyActionToPySequence(IntPtr value,
+            Type obType,
+            bool setError,
+            int size,
+            Type elementType,
+            Action<object> action)
+        {
+            if (size < 0)
+            {
+                if (setError)
+                {
+                    SetConversionError(value, obType);
+                }
+                return false;
+            }
+
             for (var i = 0; i < size; i++)
             {
                 object obj = null;
@@ -1046,15 +1098,13 @@ private static bool ToArray(IntPtr value, Type obType, out object result, bool s
                     return false;
                 }
 
-                items.SetValue(obj, i);
+                action(obj);
                 Runtime.XDecref(item);
             }
 
-            result = items;
             return true;
         }
 
-
         /// <summary>
         /// Convert a Python value to a correctly typed managed enum instance.
         /// </summary>

src/runtime/resources/clr.py

@@ -2,7 +2,7 @@
 Code in this module gets loaded into the main clr module.
 """
 
-__version__ = "1.0.5.25"
+__version__ = "1.0.5.26"
 
 
 class clrproperty(object):