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Description
Feature or enhancement
The private_PyList_Extend() function has been removed in Python 3.13: see PR#108451.
@scoderasked what is the replacement for this removed function.
The obvious replacement isPyObject_CallMethod(list, "extend", "O", arg): call thelist.extend() method. But it's slower,PyObject_CallMethod() has to get the method and decode the "O" format string.
Another replacement isPyList_SetSlice(L, PY_SSIZE_T_MAX, PY_SSIZE_T_MAX, arg) which is less straightforward, but it's efficient.
I propose adding a public PyList_Extend() function. The list type is commonly used in C extensions, it's a convenient API to create a collection when the length is not known is advance.
I don't think that performance is really the problem here sincePyList_SetSlice(L, PY_SSIZE_T_MAX, PY_SSIZE_T_MAX, arg) is available. The problem is more to more the function easier to discover and make the API easier to use. Also, it should help people to migrate away from the removed function.
There is already a publicPyDict_Update() API for the dict type, it is part of the limited C API.
If we add a function for the list type, should we also addPySet_Update() "for completeness"? The private_PySet_Update() was removed in Python 3.13.
A code search on_PyList_Extend in PyPI top 5,000 projects (2023-07-04) found 4 projects using this function:
- Cython (0.29.36)
- catboost (1.2)
- mypy (1.4.1)
- pyrsistent (0.19.3)
Logs:
PYPI-2023-07-04/catboost-1.2.tar.gz: catboost-1.2/catboost_all_src/contrib/tools/cython/Cython/Compiler/Builtin.py: BuiltinMethod("extend", "TO", "r", "__Pyx_PyList_Extend",PYPI-2023-07-04/catboost-1.2.tar.gz: catboost-1.2/catboost_all_src/contrib/tools/cython/Cython/Compiler/ExprNodes.py: extend_func = "__Pyx_PyList_Extend"PYPI-2023-07-04/catboost-1.2.tar.gz: catboost-1.2/catboost_all_src/contrib/tools/cython/Cython/Utility/Optimize.c: static CYTHON_INLINE int __Pyx_PyList_Extend(PyObject* L, PyObject* v) {PYPI-2023-07-04/catboost-1.2.tar.gz: catboost-1.2/catboost_all_src/contrib/tools/cython/Cython/Utility/Optimize.c: PyObject* none = _PyList_Extend((PyListObject*)L, v);PYPI-2023-07-04/Cython-0.29.36.tar.gz: Cython-0.29.36/Cython/Compiler/Builtin.py: BuiltinMethod("extend", "TO", "r", "__Pyx_PyList_Extend",PYPI-2023-07-04/Cython-0.29.36.tar.gz: Cython-0.29.36/Cython/Compiler/ExprNodes.py: extend_func = "__Pyx_PyList_Extend"PYPI-2023-07-04/Cython-0.29.36.tar.gz: Cython-0.29.36/Cython/Utility/Optimize.c: static CYTHON_INLINE int __Pyx_PyList_Extend(PyObject* L, PyObject* v) {PYPI-2023-07-04/Cython-0.29.36.tar.gz: Cython-0.29.36/Cython/Utility/Optimize.c: PyObject* none = _PyList_Extend((PyListObject*)L, v);PYPI-2023-07-04/mypy-1.4.1.tar.gz: mypy-1.4.1/mypyc/lib-rt/dict_ops.c: PyObject *res = _PyList_Extend((PyListObject *)list, view);PYPI-2023-07-04/mypy-1.4.1.tar.gz: mypy-1.4.1/mypyc/lib-rt/dict_ops.c: PyObject *res = _PyList_Extend((PyListObject *)list, view);PYPI-2023-07-04/mypy-1.4.1.tar.gz: mypy-1.4.1/mypyc/lib-rt/dict_ops.c: PyObject *res = _PyList_Extend((PyListObject *)list, view);PYPI-2023-07-04/mypy-1.4.1.tar.gz: mypy-1.4.1/mypyc/lib-rt/list_ops.c: return _PyList_Extend((PyListObject *)o1, o2);PYPI-2023-07-04/pyrsistent-0.19.3.tar.gz: pyrsistent-0.19.3/pvectorcmodule.c: PyObject *retVal = _PyList_Extend((PyListObject *)self->appendList, args);Cython uses the function to implement its own __Pyx_PyList_Extend() API:
staticCYTHON_INLINEint__Pyx_PyList_Extend(PyObject*L,PyObject*v) {#ifCYTHON_COMPILING_IN_CPYTHONPyObject*none=_PyList_Extend((PyListObject*)L,v);if (unlikely(!none))return-1;Py_DECREF(none);return0;#elsereturnPyList_SetSlice(L,PY_SSIZE_T_MAX,PY_SSIZE_T_MAX,v);#endif}