From c3fc7f08a0137c560840a0ebe2f2b401a83b3739 Mon Sep 17 00:00:00 2001
From: Victor Milovanov <lost@losttech.software>
Date: Fri, 19 Feb 2021 12:52:50 -0800
Subject: [PATCH 1/4] allow comparing BorrowedReference to null

---
 src/runtime/BorrowedReference.cs |  8 ++++++++
 src/runtime/importhook.cs        |  6 +++---
 src/runtime/tricks/NullOnly.cs   | 12 ++++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 src/runtime/tricks/NullOnly.cs

diff --git a/src/runtime/BorrowedReference.cs b/src/runtime/BorrowedReference.cs
index 2f5c347c7..d49f52fe9 100644
--- a/src/runtime/BorrowedReference.cs
+++ b/src/runtime/BorrowedReference.cs
@@ -28,6 +28,14 @@ public BorrowedReference(IntPtr pointer)
             => a.pointer == b.pointer;
         public static bool operator !=(BorrowedReference a, BorrowedReference b)
             => a.pointer != b.pointer;
+        public static bool operator ==(BorrowedReference reference, NullOnly @null)
+            => reference.IsNull;
+        public static bool operator !=(BorrowedReference reference, NullOnly @null)
+            => !reference.IsNull;
+        public static bool operator ==(NullOnly @null, BorrowedReference reference)
+            => reference.IsNull;
+        public static bool operator !=(NullOnly @null, BorrowedReference reference)
+            => !reference.IsNull;
 
         public override bool Equals(object obj) {
             if (obj is IntPtr ptr)
diff --git a/src/runtime/importhook.cs b/src/runtime/importhook.cs
index 066c765fe..13b45df51 100644
--- a/src/runtime/importhook.cs
+++ b/src/runtime/importhook.cs
@@ -155,7 +155,7 @@ public static unsafe NewReference GetCLRModule(BorrowedReference fromList = defa
 
             // find any items from the from list and get them from the root if they're not
             // already in the module dictionary
-            if (fromList != null && fromList != default)
+            if (fromList != null)
             {
                 if (Runtime.PyTuple_Check(fromList))
                 {
@@ -224,7 +224,7 @@ public static IntPtr __import__(IntPtr self, IntPtr argsRaw, IntPtr kw)
             if (num_args >= 4)
             {
                 fromList = Runtime.PyTuple_GetItem(args, 3);
-                if (fromList != default &&
+                if (fromList != null &&
                     Runtime.PyObject_IsTrue(fromList) == 1)
                 {
                     fromlist = true;
@@ -297,7 +297,7 @@ public static IntPtr __import__(IntPtr self, IntPtr argsRaw, IntPtr kw)
             BorrowedReference modules = Runtime.PyImport_GetModuleDict();
             BorrowedReference module = Runtime.PyDict_GetItem(modules, py_mod_name);
 
-            if (module != default)
+            if (module != null)
             {
                 if (fromlist)
                 {
diff --git a/src/runtime/tricks/NullOnly.cs b/src/runtime/tricks/NullOnly.cs
new file mode 100644
index 000000000..cc2679a61
--- /dev/null
+++ b/src/runtime/tricks/NullOnly.cs
@@ -0,0 +1,12 @@
+namespace Python.Runtime
+{
+    /// <summary>
+    /// An utility class, that can only have one value: <c>null</c>.
+    /// <para>Useful for overloading operators on structs,
+    /// that have meaningful concept of <c>null</c> value (e.g. pointers and references).</para>
+    /// </summary>
+    class NullOnly
+    {
+        private NullOnly() { }
+    }
+}

From 60bb68c2fab8bfb271dd4f7bab9e15af2a402e9c Mon Sep 17 00:00:00 2001
From: Victor Milovanov <lost@losttech.software>
Date: Fri, 19 Feb 2021 12:53:04 -0800
Subject: [PATCH 2/4] removed unused Utf8Marshaler

---
 src/runtime/CustomMarshaler.cs | 45 ----------------------------------
 1 file changed, 45 deletions(-)

diff --git a/src/runtime/CustomMarshaler.cs b/src/runtime/CustomMarshaler.cs
index 4814e6c0b..3ef5cd662 100644
--- a/src/runtime/CustomMarshaler.cs
+++ b/src/runtime/CustomMarshaler.cs
@@ -189,49 +189,4 @@ public static ICustomMarshaler GetInstance(string cookie)
             return Instance;
         }
     }
-
-
-    /// <summary>
-    /// Custom Marshaler to deal with Managed String to Native
-    /// conversion on UTF-8. Use on functions that expect UTF-8 encoded
-    /// strings like `PyUnicode_FromStringAndSize`
-    /// </summary>
-    /// <remarks>
-    /// If instead we used `MarshalAs(UnmanagedType.LPWStr)` the output to
-    /// `foo` would be `f\x00o\x00o\x00`.
-    /// </remarks>
-    internal class Utf8Marshaler : MarshalerBase
-    {
-        private static readonly MarshalerBase Instance = new Utf8Marshaler();
-        private static readonly Encoding PyEncoding = Encoding.UTF8;
-
-        public override IntPtr MarshalManagedToNative(object managedObj)
-        {
-            var s = managedObj as string;
-
-            if (s == null)
-            {
-                return IntPtr.Zero;
-            }
-
-            byte[] bStr = PyEncoding.GetBytes(s + "\0");
-            IntPtr mem = Marshal.AllocHGlobal(bStr.Length);
-            try
-            {
-                Marshal.Copy(bStr, 0, mem, bStr.Length);
-            }
-            catch (Exception)
-            {
-                Marshal.FreeHGlobal(mem);
-                throw;
-            }
-
-            return mem;
-        }
-
-        public static ICustomMarshaler GetInstance(string cookie)
-        {
-            return Instance;
-        }
-    }
 }

From 50834ba7b50247ab71f57fcc0dd475027a531003 Mon Sep 17 00:00:00 2001
From: Victor Milovanov <lost@losttech.software>
Date: Fri, 19 Feb 2021 13:28:27 -0800
Subject: [PATCH 3/4] introduced PyModule (inherits PyScope)

changed PyScope to inherit from PyObject
---
 src/embed_tests/TestFinalizer.cs       | 14 +++++-
 src/embed_tests/TestPythonException.cs |  4 +-
 src/embed_tests/TestRuntime.cs         |  4 +-
 src/embed_tests/pyimport.cs            |  4 +-
 src/embed_tests/pyinitialize.cs        |  3 +-
 src/runtime/exceptions.cs              | 21 ++++-----
 src/runtime/pymodule.cs                | 41 ++++++++++++++++
 src/runtime/pyscope.cs                 | 51 ++++++++++----------
 src/runtime/pythonengine.cs            | 65 +++++++-------------------
 src/runtime/pythonexception.cs         |  4 +-
 src/runtime/runtime.cs                 | 44 +++++++++--------
 src/runtime/runtime_state.cs           |  9 ++--
 src/testing/threadtest.cs              |  4 +-
 13 files changed, 145 insertions(+), 123 deletions(-)
 create mode 100644 src/runtime/pymodule.cs

diff --git a/src/embed_tests/TestFinalizer.cs b/src/embed_tests/TestFinalizer.cs
index 46e2fcdf1..c040e6930 100644
--- a/src/embed_tests/TestFinalizer.cs
+++ b/src/embed_tests/TestFinalizer.cs
@@ -101,7 +101,17 @@ public void CollectOnShutdown()
 
             PythonEngine.Shutdown();
             garbage = Finalizer.Instance.GetCollectedObjects();
-            Assert.IsEmpty(garbage);
+
+            if (garbage.Count > 0)
+            {
+                PythonEngine.Initialize();
+                string objects = string.Join("\n", garbage.Select(ob =>
+                {
+                    var obj = new PyObject(new BorrowedReference(ob));
+                    return $"{obj} [{obj.GetPythonType()}@{obj.Handle}]";
+                }));
+                Assert.Fail("Garbage is not empty:\n" + objects);
+            }
         }
 
         [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)] // ensure lack of references to obj
@@ -173,7 +183,7 @@ public void SimpleTestMemory()
             bool oldState = Finalizer.Instance.Enable;
             try
             {
-                using (PyObject gcModule = PythonEngine.ImportModule("gc"))
+                using (PyModule gcModule = PyModule.Import("gc"))
                 using (PyObject pyCollect = gcModule.GetAttr("collect"))
                 {
                     long span1 = CompareWithFinalizerOn(pyCollect, false);
diff --git a/src/embed_tests/TestPythonException.cs b/src/embed_tests/TestPythonException.cs
index 31addfba1..a74fc3a8b 100644
--- a/src/embed_tests/TestPythonException.cs
+++ b/src/embed_tests/TestPythonException.cs
@@ -46,7 +46,7 @@ public void TestPythonErrorTypeName()
         {
             try
             {
-                var module = PythonEngine.ImportModule("really____unknown___module");
+                var module = PyModule.Import("really____unknown___module");
                 Assert.Fail("Unknown module should not be loaded");
             }
             catch (PythonException ex)
@@ -95,7 +95,7 @@ public void TestPythonExceptionFormatNoTraceback()
         {
             try
             {
-                var module = PythonEngine.ImportModule("really____unknown___module");
+                var module = PyModule.Import("really____unknown___module");
                 Assert.Fail("Unknown module should not be loaded");
             }
             catch (PythonException ex)
diff --git a/src/embed_tests/TestRuntime.cs b/src/embed_tests/TestRuntime.cs
index 59c66cc5e..32369190c 100644
--- a/src/embed_tests/TestRuntime.cs
+++ b/src/embed_tests/TestRuntime.cs
@@ -96,7 +96,7 @@ public static void PyCheck_Iter_PyObject_IsIterable_ThreadingLock_Test()
             // TypeFlags.HaveIter set in Python 2. This tests a different code path in PyObject_IsIterable and PyIter_Check.
             var threading = Runtime.Runtime.PyImport_ImportModule("threading");
             Exceptions.ErrorCheck(threading);
-            var threadingDict = Runtime.Runtime.PyModule_GetDict(new BorrowedReference(threading));
+            var threadingDict = Runtime.Runtime.PyModule_GetDict(threading);
             Exceptions.ErrorCheck(threadingDict);
             var lockType = Runtime.Runtime.PyDict_GetItemString(threadingDict, "Lock");
             if (lockType.IsNull)
@@ -110,6 +110,8 @@ public static void PyCheck_Iter_PyObject_IsIterable_ThreadingLock_Test()
             Assert.IsFalse(Runtime.Runtime.PyObject_IsIterable(lockInstance));
             Assert.IsFalse(Runtime.Runtime.PyIter_Check(lockInstance));
 
+            threading.Dispose();
+
             Runtime.Runtime.Py_Finalize();
         }
     }
diff --git a/src/embed_tests/pyimport.cs b/src/embed_tests/pyimport.cs
index 24f31acff..b34a5d25b 100644
--- a/src/embed_tests/pyimport.cs
+++ b/src/embed_tests/pyimport.cs
@@ -52,7 +52,7 @@ public void Dispose()
         [Test]
         public void TestDottedName()
         {
-            PyObject module = PythonEngine.ImportModule("PyImportTest.test.one");
+            var module = PyModule.Import("PyImportTest.test.one");
             Assert.IsNotNull(module);
         }
 
@@ -62,7 +62,7 @@ public void TestDottedName()
         [Test]
         public void TestSysArgsImportException()
         {
-            PyObject module = PythonEngine.ImportModule("PyImportTest.sysargv");
+            var module = PyModule.Import("PyImportTest.sysargv");
             Assert.IsNotNull(module);
         }
 
diff --git a/src/embed_tests/pyinitialize.cs b/src/embed_tests/pyinitialize.cs
index c774680dd..66a9a3f7c 100644
--- a/src/embed_tests/pyinitialize.cs
+++ b/src/embed_tests/pyinitialize.cs
@@ -175,7 +175,8 @@ public static void TestRunExitFuncs()
             {
                 called = true;
             };
-            atexit.InvokeMethod("register", callback.ToPython());
+            atexit.InvokeMethod("register", callback.ToPython()).Dispose();
+            atexit.Dispose();
             Runtime.Runtime.Shutdown();
             Assert.True(called);
         }
diff --git a/src/runtime/exceptions.cs b/src/runtime/exceptions.cs
index afd0bc14e..da8653853 100644
--- a/src/runtime/exceptions.cs
+++ b/src/runtime/exceptions.cs
@@ -95,8 +95,8 @@ internal static Exception ToException(IntPtr ob)
     /// </remarks>
     public static class Exceptions
     {
-        internal static IntPtr warnings_module;
-        internal static IntPtr exceptions_module;
+        internal static PyModule warnings_module;
+        internal static PyModule exceptions_module;
 
         /// <summary>
         /// Initialization performed on startup of the Python runtime.
@@ -104,15 +104,12 @@ public static class Exceptions
         internal static void Initialize()
         {
             string exceptionsModuleName = "builtins";
-            exceptions_module = Runtime.PyImport_ImportModule(exceptionsModuleName);
-
-            Exceptions.ErrorCheck(exceptions_module);
-            warnings_module = Runtime.PyImport_ImportModule("warnings");
-            Exceptions.ErrorCheck(warnings_module);
+            exceptions_module = PyModule.Import(exceptionsModuleName);
+            warnings_module = PyModule.Import("warnings");
             Type type = typeof(Exceptions);
             foreach (FieldInfo fi in type.GetFields(BindingFlags.Public | BindingFlags.Static))
             {
-                IntPtr op = Runtime.PyObject_GetAttrString(exceptions_module, fi.Name);
+                IntPtr op = Runtime.PyObject_GetAttrString(exceptions_module.obj, fi.Name);
                 if (op != IntPtr.Zero)
                 {
                     fi.SetValue(type, op);
@@ -147,8 +144,8 @@ internal static void Shutdown()
                 Runtime.XDecref(op);
                 fi.SetValue(null, IntPtr.Zero);
             }
-            Runtime.Py_CLEAR(ref exceptions_module);
-            Runtime.Py_CLEAR(ref warnings_module);
+            exceptions_module.Dispose();
+            warnings_module.Dispose();
         }
 
         /// <summary>
@@ -348,9 +345,7 @@ public static void warn(string message, IntPtr exception, int stacklevel)
                 Exceptions.RaiseTypeError("Invalid exception");
             }
 
-            Runtime.XIncref(warnings_module);
-            IntPtr warn = Runtime.PyObject_GetAttrString(warnings_module, "warn");
-            Runtime.XDecref(warnings_module);
+            IntPtr warn = Runtime.PyObject_GetAttrString(warnings_module.obj, "warn");
             Exceptions.ErrorCheck(warn);
 
             IntPtr args = Runtime.PyTuple_New(3);
diff --git a/src/runtime/pymodule.cs b/src/runtime/pymodule.cs
new file mode 100644
index 000000000..800edb686
--- /dev/null
+++ b/src/runtime/pymodule.cs
@@ -0,0 +1,41 @@
+using System;
+
+namespace Python.Runtime
+{
+    public class PyModule : PyScope
+    {
+        internal PyModule(ref NewReference reference) : base(ref reference, PyScopeManager.Global) { }
+        public PyModule(PyObject o) : base(o.Reference, PyScopeManager.Global) { }
+
+        /// <summary>
+        /// Given a module or package name, import the
+        /// module and return the resulting module object as a <see cref="PyModule"/>.
+        /// </summary>
+        /// <param name="name">Fully-qualified module or package name</param>
+        public static PyModule Import(string name)
+        {
+            NewReference op = Runtime.PyImport_ImportModule(name);
+            PythonException.ThrowIfIsNull(op);
+            return new PyModule(ref op);
+        }
+
+        /// <summary>
+        /// Reloads the module, and returns the updated object
+        /// </summary>
+        public PyModule Reload()
+        {
+            NewReference op = Runtime.PyImport_ReloadModule(this.Reference);
+            PythonException.ThrowIfIsNull(op);
+            return new PyModule(ref op);
+        }
+
+        public static PyModule FromString(string name, string code)
+        {
+            using NewReference c = Runtime.Py_CompileString(code, "none", (int)RunFlagType.File);
+            PythonException.ThrowIfIsNull(c);
+            NewReference m = Runtime.PyImport_ExecCodeModule(name, c);
+            PythonException.ThrowIfIsNull(m);
+            return new PyModule(ref m);
+        }
+    }
+}
diff --git a/src/runtime/pyscope.cs b/src/runtime/pyscope.cs
index 9d68b76fa..4d09004bd 100644
--- a/src/runtime/pyscope.cs
+++ b/src/runtime/pyscope.cs
@@ -22,15 +22,9 @@ public class PyGILAttribute : Attribute
     }
 
     [PyGIL]
-    public class PyScope : DynamicObject, IDisposable
+    public class PyScope : PyObject
     {
-        public readonly string Name;
-
-        /// <summary>
-        /// the python Module object the scope associated with.
-        /// </summary>
-        readonly PyObject obj;
-        internal BorrowedReference Reference => obj.Reference;
+        public string Name { get; }
 
         /// <summary>
         /// the variable dict of the scope. Borrowed.
@@ -49,20 +43,24 @@ public class PyScope : DynamicObject, IDisposable
         /// </summary>
         public event Action<PyScope> OnDispose;
 
-        /// <summary>
-        /// Constructor
-        /// </summary>
-        /// <remarks>
-        /// Create a scope based on a Python Module.
-        /// </remarks>
-        internal PyScope(ref NewReference ptr, PyScopeManager manager)
+        /// <summary>Create a scope based on a Python Module.</summary>
+        internal PyScope(ref NewReference reference, PyScopeManager manager)
+            : this(reference.DangerousMoveToPointer(), manager) { }
+        /// <summary>Create a scope based on a Python Module.</summary>
+        internal PyScope(BorrowedReference reference, PyScopeManager manager)
+            : this(reference.DangerousGetAddress(), manager)
         {
-            if (!Runtime.PyType_IsSubtype(Runtime.PyObject_TYPE(ptr), Runtime.PyModuleType))
+            Runtime.XIncref(reference.DangerousGetAddress());
+        }
+
+        /// <summary>Create a scope based on a Python Module.</summary>
+        private PyScope(IntPtr ptr, PyScopeManager manager) : base(ptr)
+        {
+            if (!Runtime.PyType_IsSubtype(Runtime.PyObject_TYPE(Reference), Runtime.PyModuleType))
             {
                 throw new PyScopeException("object is not a module");
             }
             Manager = manager ?? PyScopeManager.Global;
-            obj = ptr.MoveToPyObject();
             //Refcount of the variables not increase
             variables = Runtime.PyModule_GetDict(Reference).DangerousGetAddress();
             PythonException.ThrowIfIsNull(variables);
@@ -72,7 +70,8 @@ internal PyScope(ref NewReference ptr, PyScopeManager manager)
                 Runtime.PyEval_GetBuiltins()
             );
             PythonException.ThrowIfIsNotZero(res);
-            this.Name = this.Get<string>("__name__");
+            using var name = this.Get("__name__");
+            this.Name = name.As<string>();
         }
 
         /// <summary>
@@ -118,7 +117,7 @@ public dynamic Import(string name, string asname = null)
             }
             else
             {
-                PyObject module = PythonEngine.ImportModule(name);
+                var module = PyModule.Import(name);
                 Import(module, asname);
                 return module;
             }
@@ -132,7 +131,7 @@ public dynamic Import(string name, string asname = null)
         /// </remarks>
         public void Import(PyScope scope, string asname)
         {
-            this.SetPyValue(asname, scope.obj.Handle);
+            this.SetPyValue(asname, scope.Handle);
         }
 
         /// <summary>
@@ -169,7 +168,7 @@ public void ImportAll(string name)
             }
             else
             {
-                PyObject module = PythonEngine.ImportModule(name);
+                var module = PyModule.Import(name);
                 ImportAll(module);
             }
         }
@@ -503,16 +502,20 @@ public override bool TrySetMember(SetMemberBinder binder, object value)
 
         private void Check()
         {
-            if (this.obj.IsDisposed)
+            if (this.obj == IntPtr.Zero)
             {
                 throw new PyScopeException($"The scope of name '{Name}' object has been disposed");
             }
         }
 
-        public void Dispose()
+        protected override void Dispose(bool disposing)
         {
+            if (this.obj == IntPtr.Zero)
+            {
+                return;
+            }
+            base.Dispose(disposing);
             this.OnDispose?.Invoke(this);
-            this.obj.Dispose();
         }
     }
 
diff --git a/src/runtime/pythonengine.cs b/src/runtime/pythonengine.cs
index 35ea3f6d2..b12309733 100644
--- a/src/runtime/pythonengine.cs
+++ b/src/runtime/pythonengine.cs
@@ -468,62 +468,27 @@ public static void EndAllowThreads(IntPtr ts)
             Runtime.PyEval_RestoreThread(ts);
         }
 
+        [Obsolete("Use PyModule.Import")]
+        public static PyObject ImportModule(string name) => PyModule.Import(name);
 
-        /// <summary>
-        /// ImportModule Method
-        /// </summary>
-        /// <remarks>
-        /// Given a fully-qualified module or package name, import the
-        /// module and return the resulting module object as a PyObject
-        /// or null if an exception is raised.
-        /// </remarks>
-        public static PyObject ImportModule(string name)
-        {
-            IntPtr op = Runtime.PyImport_ImportModule(name);
-            PythonException.ThrowIfIsNull(op);
-            return new PyObject(op);
-        }
-
-
-        /// <summary>
-        /// ReloadModule Method
-        /// </summary>
-        /// <remarks>
-        /// Given a PyObject representing a previously loaded module, reload
-        /// the module.
-        /// </remarks>
+        [Obsolete("Use PyModule.Reload")]
         public static PyObject ReloadModule(PyObject module)
-        {
-            IntPtr op = Runtime.PyImport_ReloadModule(module.Handle);
-            PythonException.ThrowIfIsNull(op);
-            return new PyObject(op);
-        }
+            => module is PyModule pyModule ? pyModule.Reload() : new PyModule(module).Reload();
 
-
-        /// <summary>
-        /// ModuleFromString Method
-        /// </summary>
-        /// <remarks>
-        /// Given a string module name and a string containing Python code,
-        /// execute the code in and return a module of the given name.
-        /// </remarks>
+        [Obsolete("Use PyModule.FromString")]
         public static PyObject ModuleFromString(string name, string code)
-        {
-            IntPtr c = Runtime.Py_CompileString(code, "none", (int)RunFlagType.File);
-            PythonException.ThrowIfIsNull(c);
-            IntPtr m = Runtime.PyImport_ExecCodeModule(name, c);
-            PythonException.ThrowIfIsNull(m);
-            return new PyObject(m);
-        }
+            => PyModule.FromString(name, code);
+
 
         public static PyObject Compile(string code, string filename = "", RunFlagType mode = RunFlagType.File)
         {
             var flag = (int)mode;
-            IntPtr ptr = Runtime.Py_CompileString(code, filename, flag);
+            NewReference ptr = Runtime.Py_CompileString(code, filename, flag);
             PythonException.ThrowIfIsNull(ptr);
-            return new PyObject(ptr);
+            return ptr.MoveToPyObject();
         }
 
+
         /// <summary>
         /// Eval Method
         /// </summary>
@@ -742,10 +707,12 @@ public static KeywordArguments kw(params object[] kv)
             return dict;
         }
 
-        public static PyObject Import(string name)
-        {
-            return PythonEngine.ImportModule(name);
-        }
+        /// <summary>
+        /// Given a module or package name, import the
+        /// module and return the resulting module object as a <see cref="PyModule"/>.
+        /// </summary>
+        /// <param name="name">Fully-qualified module or package name</param>
+        public static PyModule Import(string name) => PyModule.Import(name);
 
         public static void SetArgv()
         {
diff --git a/src/runtime/pythonexception.cs b/src/runtime/pythonexception.cs
index 7dd4f0811..648888293 100644
--- a/src/runtime/pythonexception.cs
+++ b/src/runtime/pythonexception.cs
@@ -48,7 +48,7 @@ public PythonException()
 
             if (_pyTB != IntPtr.Zero)
             {
-                using PyObject tb_module = PythonEngine.ImportModule("traceback");
+                using var tb_module = PyModule.Import("traceback");
 
                 Runtime.XIncref(_pyTB);
                 using var pyTB = new PyObject(_pyTB);
@@ -198,7 +198,7 @@ public string Format()
                     using (PyObject pyType = new PyObject(type))
                     using (PyObject pyValue = new PyObject(value))
                     using (PyObject pyTB = new PyObject(tb))
-                    using (PyObject tb_mod = PythonEngine.ImportModule("traceback"))
+                    using (PyObject tb_mod = PyModule.Import("traceback"))
                     {
                         var buffer = new StringBuilder();
                         var values = tb_mod.InvokeMethod("format_exception", pyType, pyValue, pyTB);
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
index ec7f5e446..173bd294d 100644
--- a/src/runtime/runtime.cs
+++ b/src/runtime/runtime.cs
@@ -278,9 +278,8 @@ private static void InitPyMembers()
 
             _PyObject_NextNotImplemented = Get_PyObject_NextNotImplemented();
             {
-                IntPtr sys = PyImport_ImportModule("sys");
-                PyModuleType = PyObject_Type(sys);
-                XDecref(sys);
+                using var sys = PyImport_ImportModule("sys");
+                PyModuleType = PyObject_Type(sys.DangerousMoveToPointer());
             }
         }
 
@@ -937,14 +936,14 @@ internal static NewReference PyRun_String(string code, RunFlagType st, BorrowedR
         /// Return value: New reference.
         /// This is a simplified interface to Py_CompileStringFlags() below, leaving flags set to NULL.
         /// </summary>
-        internal static IntPtr Py_CompileString(string str, string file, int start)
+        internal static NewReference Py_CompileString(string str, string file, int start)
         {
             using var strPtr = new StrPtr(str, Encoding.UTF8);
             using var fileObj = new PyString(file);
             return Delegates.Py_CompileStringObject(strPtr, fileObj.Reference, start, Utf8String, -1);
         }
 
-        internal static IntPtr PyImport_ExecCodeModule(string name, IntPtr code)
+        internal static NewReference PyImport_ExecCodeModule(string name, BorrowedReference code)
         {
             using var namePtr = new StrPtr(name, Encoding.UTF8);
             return Delegates.PyImport_ExecCodeModule(namePtr, code);
@@ -1027,11 +1026,18 @@ internal static int PyObject_HasAttrString(BorrowedReference pointer, string nam
         internal static IntPtr PyObject_GetAttrString(IntPtr pointer, string name)
         {
             using var namePtr = new StrPtr(name, Encoding.UTF8);
-            return Delegates.PyObject_GetAttrString(pointer, namePtr);
+            return Delegates.PyObject_GetAttrString(new BorrowedReference(pointer), namePtr)
+                .DangerousMoveToPointerOrNull();
         }
 
+        internal static NewReference PyObject_GetAttrString(BorrowedReference pointer, string name)
+        {
+            using var namePtr = new StrPtr(name, Encoding.UTF8);
+            return Delegates.PyObject_GetAttrString(pointer, namePtr);
+        }
 
-        internal static IntPtr PyObject_GetAttrString(IntPtr pointer, StrPtr name) => Delegates.PyObject_GetAttrString(pointer, name);
+        internal static NewReference PyObject_GetAttrString(BorrowedReference pointer, StrPtr name)
+            => Delegates.PyObject_GetAttrString(pointer, name);
 
 
         internal static int PyObject_SetAttrString(IntPtr pointer, string name, IntPtr value)
@@ -1917,13 +1923,13 @@ internal static string PyModule_GetFilename(IntPtr module)
         /// Return value: New reference.
         /// </summary>
 
-        internal static IntPtr PyImport_ImportModule(string name)
+        internal static NewReference PyImport_ImportModule(string name)
         {
             using var namePtr = new StrPtr(name, Encoding.UTF8);
             return Delegates.PyImport_ImportModule(namePtr);
         }
 
-        internal static IntPtr PyImport_ReloadModule(IntPtr module) => Delegates.PyImport_ReloadModule(module);
+        internal static NewReference PyImport_ReloadModule(BorrowedReference module) => Delegates.PyImport_ReloadModule(module);
 
 
         internal static BorrowedReference PyImport_AddModule(string name)
@@ -2294,13 +2300,13 @@ static Delegates()
                 PyRun_SimpleStringFlags = (delegate* unmanaged[Cdecl]<StrPtr, in PyCompilerFlags, int>)GetFunctionByName(nameof(PyRun_SimpleStringFlags), GetUnmanagedDll(_PythonDll));
                 PyRun_StringFlags = (delegate* unmanaged[Cdecl]<StrPtr, RunFlagType, BorrowedReference, BorrowedReference, in PyCompilerFlags, NewReference>)GetFunctionByName(nameof(PyRun_StringFlags), GetUnmanagedDll(_PythonDll));
                 PyEval_EvalCode = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr>)GetFunctionByName(nameof(PyEval_EvalCode), GetUnmanagedDll(_PythonDll));
-                Py_CompileStringObject = (delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, int, in PyCompilerFlags, int, IntPtr>)GetFunctionByName(nameof(Py_CompileStringObject), GetUnmanagedDll(_PythonDll));
-                PyImport_ExecCodeModule = (delegate* unmanaged[Cdecl]<StrPtr, IntPtr, IntPtr>)GetFunctionByName(nameof(PyImport_ExecCodeModule), GetUnmanagedDll(_PythonDll));
+                Py_CompileStringObject = (delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, int, in PyCompilerFlags, int, NewReference>)GetFunctionByName(nameof(Py_CompileStringObject), GetUnmanagedDll(_PythonDll));
+                PyImport_ExecCodeModule = (delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, NewReference>)GetFunctionByName(nameof(PyImport_ExecCodeModule), GetUnmanagedDll(_PythonDll));
                 PyCFunction_NewEx = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr>)GetFunctionByName(nameof(PyCFunction_NewEx), GetUnmanagedDll(_PythonDll));
                 PyCFunction_Call = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr>)GetFunctionByName(nameof(PyCFunction_Call), GetUnmanagedDll(_PythonDll));
                 PyMethod_New = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr>)GetFunctionByName(nameof(PyMethod_New), GetUnmanagedDll(_PythonDll));
                 PyObject_HasAttrString = (delegate* unmanaged[Cdecl]<BorrowedReference, StrPtr, int>)GetFunctionByName(nameof(PyObject_HasAttrString), GetUnmanagedDll(_PythonDll));
-                PyObject_GetAttrString = (delegate* unmanaged[Cdecl]<IntPtr, StrPtr, IntPtr>)GetFunctionByName(nameof(PyObject_GetAttrString), GetUnmanagedDll(_PythonDll));
+                PyObject_GetAttrString = (delegate* unmanaged[Cdecl]<BorrowedReference, StrPtr, NewReference>)GetFunctionByName(nameof(PyObject_GetAttrString), GetUnmanagedDll(_PythonDll));
                 PyObject_SetAttrString = (delegate* unmanaged[Cdecl]<IntPtr, StrPtr, IntPtr, int>)GetFunctionByName(nameof(PyObject_SetAttrString), GetUnmanagedDll(_PythonDll));
                 PyObject_HasAttr = (delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int>)GetFunctionByName(nameof(PyObject_HasAttr), GetUnmanagedDll(_PythonDll));
                 PyObject_GetAttr = (delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, NewReference>)GetFunctionByName(nameof(PyObject_GetAttr), GetUnmanagedDll(_PythonDll));
@@ -2458,8 +2464,8 @@ static Delegates()
                 PyModule_GetFilename = (delegate* unmanaged[Cdecl]<IntPtr, StrPtr>)GetFunctionByName(nameof(PyModule_GetFilename), GetUnmanagedDll(_PythonDll));
                 PyModule_Create2 = (delegate* unmanaged[Cdecl]<IntPtr, int, IntPtr>)GetFunctionByName(nameof(PyModule_Create2), GetUnmanagedDll(_PythonDll));
                 PyImport_Import = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr>)GetFunctionByName(nameof(PyImport_Import), GetUnmanagedDll(_PythonDll));
-                PyImport_ImportModule = (delegate* unmanaged[Cdecl]<StrPtr, IntPtr>)GetFunctionByName(nameof(PyImport_ImportModule), GetUnmanagedDll(_PythonDll));
-                PyImport_ReloadModule = (delegate* unmanaged[Cdecl]<IntPtr, IntPtr>)GetFunctionByName(nameof(PyImport_ReloadModule), GetUnmanagedDll(_PythonDll));
+                PyImport_ImportModule = (delegate* unmanaged[Cdecl]<StrPtr, NewReference>)GetFunctionByName(nameof(PyImport_ImportModule), GetUnmanagedDll(_PythonDll));
+                PyImport_ReloadModule = (delegate* unmanaged[Cdecl]<BorrowedReference, NewReference>)GetFunctionByName(nameof(PyImport_ReloadModule), GetUnmanagedDll(_PythonDll));
                 PyImport_AddModule = (delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference>)GetFunctionByName(nameof(PyImport_AddModule), GetUnmanagedDll(_PythonDll));
                 PyImport_GetModuleDict = (delegate* unmanaged[Cdecl]<BorrowedReference>)GetFunctionByName(nameof(PyImport_GetModuleDict), GetUnmanagedDll(_PythonDll));
                 PySys_SetArgvEx = (delegate* unmanaged[Cdecl]<int, IntPtr, int, void>)GetFunctionByName(nameof(PySys_SetArgvEx), GetUnmanagedDll(_PythonDll));
@@ -2566,13 +2572,13 @@ static Delegates()
             internal static delegate* unmanaged[Cdecl]<StrPtr, in PyCompilerFlags, int> PyRun_SimpleStringFlags { get; }
             internal static delegate* unmanaged[Cdecl]<StrPtr, RunFlagType, BorrowedReference, BorrowedReference, in PyCompilerFlags, NewReference> PyRun_StringFlags { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr> PyEval_EvalCode { get; }
-            internal static delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, int, in PyCompilerFlags, int, IntPtr> Py_CompileStringObject { get; }
-            internal static delegate* unmanaged[Cdecl]<StrPtr, IntPtr, IntPtr> PyImport_ExecCodeModule { get; }
+            internal static delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, int, in PyCompilerFlags, int, NewReference> Py_CompileStringObject { get; }
+            internal static delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference, NewReference> PyImport_ExecCodeModule { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr> PyCFunction_NewEx { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr> PyCFunction_Call { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr> PyMethod_New { get; }
             internal static delegate* unmanaged[Cdecl]<BorrowedReference, StrPtr, int> PyObject_HasAttrString { get; }
-            internal static delegate* unmanaged[Cdecl]<IntPtr, StrPtr, IntPtr> PyObject_GetAttrString { get; }
+            internal static delegate* unmanaged[Cdecl]<BorrowedReference, StrPtr, NewReference> PyObject_GetAttrString { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, StrPtr, IntPtr, int> PyObject_SetAttrString { get; }
             internal static delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int> PyObject_HasAttr { get; }
             internal static delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, NewReference> PyObject_GetAttr { get; }
@@ -2723,8 +2729,8 @@ static Delegates()
             internal static delegate* unmanaged[Cdecl]<IntPtr, StrPtr> PyModule_GetFilename { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, int, IntPtr> PyModule_Create2 { get; }
             internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr> PyImport_Import { get; }
-            internal static delegate* unmanaged[Cdecl]<StrPtr, IntPtr> PyImport_ImportModule { get; }
-            internal static delegate* unmanaged[Cdecl]<IntPtr, IntPtr> PyImport_ReloadModule { get; }
+            internal static delegate* unmanaged[Cdecl]<StrPtr, NewReference> PyImport_ImportModule { get; }
+            internal static delegate* unmanaged[Cdecl]<BorrowedReference, NewReference> PyImport_ReloadModule { get; }
             internal static delegate* unmanaged[Cdecl]<StrPtr, BorrowedReference> PyImport_AddModule { get; }
             internal static delegate* unmanaged[Cdecl]<BorrowedReference> PyImport_GetModuleDict { get; }
             internal static delegate* unmanaged[Cdecl]<int, IntPtr, int, void> PySys_SetArgvEx { get; }
diff --git a/src/runtime/runtime_state.cs b/src/runtime/runtime_state.cs
index 295219675..b541a7c44 100644
--- a/src/runtime/runtime_state.cs
+++ b/src/runtime/runtime_state.cs
@@ -139,18 +139,15 @@ private static void RestoreObjects(IntPtr dummyGC)
 
         public static IEnumerable<IntPtr> PyGCGetObjects()
         {
-            var gc = PyImport_ImportModule("gc");
-            PythonException.ThrowIfIsNull(gc);
-            var get_objects = PyObject_GetAttrString(gc, "get_objects");
-            var objs = PyObject_CallObject(get_objects, IntPtr.Zero);
+            using var gc = PyModule.Import("gc");
+            using var get_objects = gc.GetAttr("get_objects");
+            var objs = PyObject_CallObject(get_objects.Handle, IntPtr.Zero);
             var length = PyList_Size(new BorrowedReference(objs));
             for (long i = 0; i < length; i++)
             {
                 var obj = PyList_GetItem(new BorrowedReference(objs), i);
                 yield return obj.DangerousGetAddress();
             }
-            XDecref(objs);
-            XDecref(gc);
         }
 
         public static IEnumerable<IntPtr> GetModuleNames()
diff --git a/src/testing/threadtest.cs b/src/testing/threadtest.cs
index 9c76929b2..6664c3643 100644
--- a/src/testing/threadtest.cs
+++ b/src/testing/threadtest.cs
@@ -34,7 +34,7 @@ public static string CallEchoString(string arg)
             {
                 if (module == null)
                 {
-                    module = PythonEngine.ModuleFromString("tt", testmod);
+                    module = PyModule.FromString("tt", testmod);
                 }
                 PyObject func = module.GetAttr("echostring");
                 var parg = new PyString(arg);
@@ -58,7 +58,7 @@ public static string CallEchoString2(string arg)
             {
                 if (module == null)
                 {
-                    module = PythonEngine.ModuleFromString("tt", testmod);
+                    module = PyModule.FromString("tt", testmod);
                 }
 
                 PyObject func = module.GetAttr("echostring2");

From ac68aab1374b2553e05e6e4cec87753e83c15f41 Mon Sep 17 00:00:00 2001
From: Victor Milovanov <lost@losttech.software>
Date: Fri, 19 Feb 2021 15:08:59 -0800
Subject: [PATCH 4/4] minor fixes

---
 src/embed_tests/GlobalTestsSetup.cs     | 2 +-
 src/embed_tests/TestNativeTypeOffset.cs | 2 +-
 src/runtime/pystring.cs                 | 5 +----
 3 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/embed_tests/GlobalTestsSetup.cs b/src/embed_tests/GlobalTestsSetup.cs
index 458ab6a99..9a832cb0c 100644
--- a/src/embed_tests/GlobalTestsSetup.cs
+++ b/src/embed_tests/GlobalTestsSetup.cs
@@ -7,7 +7,7 @@ namespace Python.EmbeddingTest
     // As the SetUpFixture, the OneTimeTearDown of this class is executed after
     // all tests have run.
     [SetUpFixture]
-    public class GlobalTestsSetup
+    public partial class GlobalTestsSetup
     {
         [OneTimeTearDown]
         public void FinalCleanup()
diff --git a/src/embed_tests/TestNativeTypeOffset.cs b/src/embed_tests/TestNativeTypeOffset.cs
index 7dd5a765e..8efd16e02 100644
--- a/src/embed_tests/TestNativeTypeOffset.cs
+++ b/src/embed_tests/TestNativeTypeOffset.cs
@@ -9,7 +9,7 @@
 
 using Python.Runtime;
 
-namespace Python.EmbeddingPythonTest
+namespace Python.EmbeddingTest
 {
     public class TestNativeTypeOffset
     {
diff --git a/src/runtime/pystring.cs b/src/runtime/pystring.cs
index b3d0dc86d..07eabba14 100644
--- a/src/runtime/pystring.cs
+++ b/src/runtime/pystring.cs
@@ -67,11 +67,8 @@ public PyString(string s) : base(FromString(s))
 
 
         /// <summary>
-        /// IsStringType Method
-        /// </summary>
-        /// <remarks>
         /// Returns true if the given object is a Python string.
-        /// </remarks>
+        /// </summary>
         public static bool IsStringType(PyObject value)
         {
             return Runtime.PyString_Check(value.obj);

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