Drop C module dependency when getting _PyObject_NextNotImplemented

amos402 · amos402 · commit 32e446ee6f1a · 2019-11-30T19:47:04.000+08:00
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
@@ -292,23 +292,18 @@ internal static void Initialize(bool initSigs = false)
 
             Error = new IntPtr(-1);
 
+            _PyObject_NextNotImplemented = Get_PyObject_NextNotImplemented();
+            {
+                IntPtr sys = PyImport_ImportModule("sys");
+                PyModuleType = PyObject_Type(sys);
+                XDecref(sys);
+            }
+
             // Initialize data about the platform we're running on. We need
             // this for the type manager and potentially other details. Must
             // happen after caching the python types, above.
             InitializePlatformData();
 
-            // Since `_PyObject_NextNotImplemented` would set to a heap class
-            // for tp_iternext which doesn't implement __next__.
-            // Thus we need a heap class to get it, the ZipImportError is a
-            // heap class and it's in builtins, so we can use it as a trick.
-            var zipimport = PyImport_ImportModule("zipimport");
-            var ZipImportError = PyObject_GetAttrString(zipimport, "ZipImportError");
-            _PyObject_NextNotImplemented = Marshal.ReadIntPtr(ZipImportError, TypeOffset.tp_iternext);
-            XDecref(ZipImportError);
-            XDecref(zipimport);
-
-            PyModuleType = PyObject_Type(zipimport);
-
             // Initialize modules that depend on the runtime class.
             AssemblyManager.Initialize();
             PyCLRMetaType = MetaType.Initialize();
@@ -325,6 +320,24 @@ internal static void Initialize(bool initSigs = false)
             AssemblyManager.UpdatePath();
         }
 
+        private static IntPtr Get_PyObject_NextNotImplemented()
+        {
+            IntPtr globals = PyDict_New();
+            const string code = "class A(object): pass";
+            IntPtr res = PyRun_String(code, (IntPtr)RunFlagType.File, globals, globals);
+            if (res == IntPtr.Zero)
+            {
+                XDecref(globals);
+                throw new PythonException();
+            }
+            XDecref(res);
+            IntPtr A = PyDict_GetItemString(globals, "A");
+            IntPtr iternext =  Marshal.ReadIntPtr(A, TypeOffset.tp_iternext);
+            XDecref(globals);
+            XDecref(A);
+            return iternext;
+        }
+
         /// <summary>
         /// Initializes the data about platforms.
         ///
