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/Modules/_curses_panel.c b/Modules/_curses_panel.c
index 94caf8c..0b328f9 100644
--- a/Modules/_curses_panel.c
+++ b/Modules/_curses_panel.c
@@ -520,7 +520,7 @@ static PyType_Slot PyCursesPanel_Type_slots[] = {
static PyType_Spec PyCursesPanel_Type_spec = {
.name = "_curses_panel.panel",
.basicsize = sizeof(PyCursesPanelObject),
- .flags = Py_TPFLAGS_DEFAULT,
+ .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION,
.slots = PyCursesPanel_Type_slots
};
@@ -656,7 +656,6 @@ _curses_panel_exec(PyObject *mod)
if (state->PyCursesPanel_Type == NULL) {
return -1;
}
- ((PyTypeObject *)state->PyCursesPanel_Type)->tp_new = NULL;
if (PyModule_AddType(mod, state->PyCursesPanel_Type) < 0) {
return -1;