bpo-43916: Add Py_TPFLAGS_DISALLOW_INSTANTIATION type flag (GH-25721)
Add a new Py_TPFLAGS_DISALLOW_INSTANTIATION type flag to disallow
creating type instances: set tp_new to NULL and don't create the
"__new__" key in the type dictionary.
The flag is set automatically on static types if tp_base is NULL or
&PyBaseObject_Type and tp_new is NULL.
Use the flag on the following types:
* _curses.ncurses_version type
* _curses_panel.panel
* _tkinter.Tcl_Obj
* _tkinter.tkapp
* _tkinter.tktimertoken
* _xxsubinterpretersmodule.ChannelID
* sys.flags type
* sys.getwindowsversion() type
* sys.version_info type
Update MyStr example in the C API documentation to use
Py_TPFLAGS_DISALLOW_INSTANTIATION.
Add _PyStructSequence_InitType() function to create a structseq type
with the Py_TPFLAGS_DISALLOW_INSTANTIATION flag set.
type_new() calls _PyType_CheckConsistency() at exit.
diff --git a/Include/object.h b/Include/object.h
index cffe72c..4c06999 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -327,6 +327,10 @@ given type object has a specified feature.
#define Py_TPFLAGS_MAPPING (1 << 6)
#endif
+/* Disallow creating instances of the type: set tp_new to NULL and don't create
+ * the "__new__" key in the type dictionary. */
+#define Py_TPFLAGS_DISALLOW_INSTANTIATION (1UL << 7)
+
/* Set if the type object is immutable: type attributes cannot be set nor deleted */
#define Py_TPFLAGS_IMMUTABLETYPE (1UL << 8)
diff --git a/Include/structseq.h b/Include/structseq.h
index 8f51c89..af3af41 100644
--- a/Include/structseq.h
+++ b/Include/structseq.h
@@ -27,6 +27,12 @@ PyAPI_FUNC(void) PyStructSequence_InitType(PyTypeObject *type,
PyAPI_FUNC(int) PyStructSequence_InitType2(PyTypeObject *type,
PyStructSequence_Desc *desc);
#endif
+#ifdef Py_BUILD_CORE
+extern int _PyStructSequence_InitType(
+ PyTypeObject *type,
+ PyStructSequence_Desc *desc,
+ unsigned long tp_flags);
+#endif
PyAPI_FUNC(PyTypeObject*) PyStructSequence_NewType(PyStructSequence_Desc *desc);
PyAPI_FUNC(PyObject *) PyStructSequence_New(PyTypeObject* type);