Convert static initializers of PyTypeObjects to use C99 Designated (named) initializers #127679
Description
Named initializer are both easier to read and less error prone. There is AFAICT no downside to using them.
However, we have been historically reluctant to change code for purely maintenance. Personally, I think this leads to poorer code quality, but others value cleaner code history more.
In this case I think the readability and correctness advantages are such that we should make this change and accept the inconvenience in version control history.
As a motivating example, take the bool type, PyBool_Type:
PyTypeObject PyBool_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"bool",
offsetof(struct _longobject, long_value.ob_digit), /* tp_basicsize */
sizeof(digit), /* tp_itemsize */
bool_dealloc, /* tp_dealloc */
0, /* tp_vectorcall_offset */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_as_async */
bool_repr, /* tp_repr */
&bool_as_number, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
bool_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
0, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
&PyLong_Type, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
bool_new, /* tp_new */
.tp_vectorcall = bool_vectorcall,
};There are a lot of zeros, and a lot of comments to make sure we have the right number of zeros. If one is missing, things go wrong.
Contrast that with the C99 version:
PyTypeObject PyBool_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
.tp_name = "bool",
.tp_basicsize = offsetof(struct _longobject, long_value.ob_digit),
.tp_itemsize = sizeof(digit),
.tp_flags = Py_TPFLAGS_DEFAULT,
.tp_as_number = &bool_as_number,
.tp_base = &PyLong_Type,
.tp_dealloc = bool_dealloc,
.tp_doc = bool_doc,
.tp_new = bool_new,
.tp_repr = bool_repr,
.tp_vectorcall = bool_vectorcall,
};
The code is self describing (no need for comments naming the fields) and is much less error prone. The fields can listed in any order, in this case with the core field first, then the optional fields alphabetically.