Feature or enhancement

Proposal:

When implementing an extension module with a module state enabled,
binary tp slot functions (e.g. nb_add) need two PyType_GetModuleByDef() to be used like the following to compare the given types with a heap-type object in the module state, which can be slow:

static PyObject *
foo_add(PyObject *left, PyObject *right)
{
    ...
    PyObject *module = PyType_GetModuleByDef(Py_TYPE(left), &module_def);
    if (module == NULL) {
        PyErr_Clear();
        module = PyType_GetModuleByDef(Py_TYPE(right), &module_def);
    }
    ...
}

• 3.13.0 alpha5 _decimal (module state ver.)

from timeit import timeit
f = lambda s: timeit(s, 'import _decimal; d = _decimal.Decimal(1)')
a = f('d + 1')
b = f('1 + d')
print('d + 1:', a)
print('1 + d:', b,  b / a)

d + 1: 0.11202071857405826
1 + d: 0.49533294743326095 4.421797625818569

The difference mainly comes from a TypeError emission from PyType_GetModuleByDef(), so it would be nice if we could have a new function which receives two types and emits an error after checking them.

cc @encukou

Related issue:

• Isolate Stdlib Extension Modules #103092

Linked PRs

• gh-117578: Introduce _PyType_GetModuleByDef2 private function #117661
• gh-117578: Fix inlining regression in PyType_GetModuleByDef() #123100