reimplement remoting check with .NET standard-compatible reflection (pythonnet#1170)

koubaa · AlexCatarino · commit 0832c433b678 · 2020-06-30T00:42:45.000+01:00
diff --git a/src/runtime/converter.cs b/src/runtime/converter.cs
@@ -146,6 +146,23 @@ internal static IntPtr ToPython<T>(T value)
             return ToPython(value, typeof(T));
         }
 
+        private static readonly Func<object, bool> IsTransparentProxy = GetIsTransparentProxy();
+
+        private static bool Never(object _) => false;
+
+        private static Func<object, bool> GetIsTransparentProxy()
+        {
+            var remoting = typeof(int).Assembly.GetType("System.Runtime.Remoting.RemotingServices");
+            if (remoting is null) return Never;
+
+            var isProxy = remoting.GetMethod("IsTransparentProxy", new[] { typeof(object) });
+            if (isProxy is null) return Never;
+
+            return (Func<object, bool>)Delegate.CreateDelegate(
+              typeof(Func<object, bool>), isProxy,
+              throwOnBindFailure: true);
+        }
+
         internal static IntPtr ToPython(object value, Type type)
         {
             if (value is PyObject)
@@ -198,15 +215,8 @@ internal static IntPtr ToPython(object value, Type type)
             var pyderived = value as IPythonDerivedType;
             if (null != pyderived)
             {
-                #if NETSTANDARD
-                return ClassDerivedObject.ToPython(pyderived);
-                #else
-                // if object is remote don't do this
-                if (!System.Runtime.Remoting.RemotingServices.IsTransparentProxy(pyderived))
-                {
+                if (!IsTransparentProxy(pyderived))
                     return ClassDerivedObject.ToPython(pyderived);
-                }
-                #endif
             }
 
             // hmm - from Python, we almost never care what the declared
