[issue14189] Documentation for some C APIs is missing clear specification of the type of reference they return
New submission from Baruch Sterin <python@bsterin.com>: In addition to the description text, most C API functions have a one-line, emphasized specification whether they return a new or a borrowed reference. (e.g. 'Return value: New reference.'). The following API functions are missing that. Some of them, like PyMemoryView_FromBuffer(), have descriptions that are clear, but it would still be nice to have an unambiguous statement like most other API functions have. The list has been generated automatically, so it might contain some errors. Doc/c-api/arg.rst: Py_VaBuildValue Doc/c-api/buffer.rst: PyMemoryView_FromBuffer Doc/c-api/buffer.rst: PyMemoryView_FromObject Doc/c-api/buffer.rst: PyMemoryView_GetContiguous Doc/c-api/bytearray.rst: PyByteArray_Concat Doc/c-api/bytearray.rst: PyByteArray_FromObject Doc/c-api/bytearray.rst: PyByteArray_FromStringAndSize Doc/c-api/code.rst: PyCode_New Doc/c-api/codec.rst: PyCodec_BackslashReplaceErrors Doc/c-api/codec.rst: PyCodec_Decode Doc/c-api/codec.rst: PyCodec_Decoder Doc/c-api/codec.rst: PyCodec_Encode Doc/c-api/codec.rst: PyCodec_Encoder Doc/c-api/codec.rst: PyCodec_IgnoreErrors Doc/c-api/codec.rst: PyCodec_IncrementalDecoder Doc/c-api/codec.rst: PyCodec_IncrementalEncoder Doc/c-api/codec.rst: PyCodec_LookupError Doc/c-api/codec.rst: PyCodec_ReplaceErrors Doc/c-api/codec.rst: PyCodec_StreamReader Doc/c-api/codec.rst: PyCodec_StreamWriter Doc/c-api/codec.rst: PyCodec_StrictErrors Doc/c-api/codec.rst: PyCodec_XMLCharRefReplaceErrors Doc/c-api/exceptions.rst: PyUnicodeDecodeError_Create Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetEncoding Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetObject Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetReason Doc/c-api/exceptions.rst: PyUnicodeEncodeError_Create Doc/c-api/exceptions.rst: PyUnicodeTranslateError_Create Doc/c-api/float.rst: PyFloat_GetInfo Doc/c-api/import.rst: PyImport_GetImporter Doc/c-api/import.rst: PyImport_ImportModuleNoBlock Doc/c-api/import.rst: _PyImport_FindExtension Doc/c-api/import.rst: _PyImport_FixupExtension Doc/c-api/init.rst: PyEval_GetCallStats Doc/c-api/int.rst: PyInt_FromSize_t Doc/c-api/long.rst: PyLong_FromSize_t Doc/c-api/long.rst: PyLong_FromSsize_t Doc/c-api/number.rst: PyNumber_Index Doc/c-api/number.rst: PyNumber_ToBase Doc/c-api/object.rst: PyObject_Bytes Doc/c-api/object.rst: PyObject_GenericGetAttr Doc/c-api/unicode.rst: PyUnicode_AsUTF32String Doc/c-api/unicode.rst: PyUnicode_DecodeMBCSStateful Doc/c-api/unicode.rst: PyUnicode_DecodeUTF32 Doc/c-api/unicode.rst: PyUnicode_DecodeUTF32Stateful Doc/c-api/unicode.rst: PyUnicode_DecodeUTF7 Doc/c-api/unicode.rst: PyUnicode_DecodeUTF7Stateful Doc/c-api/unicode.rst: PyUnicode_EncodeUTF32 Doc/c-api/unicode.rst: PyUnicode_EncodeUTF7 Doc/c-api/veryhigh.rst: PyEval_EvalCodeEx Doc/c-api/veryhigh.rst: PyEval_EvalFrame Doc/c-api/veryhigh.rst: PyEval_EvalFrameEx ---------- assignee: docs@python components: Documentation messages: 154877 nosy: baruch.sterin, docs@python priority: normal severity: normal status: open title: Documentation for some C APIs is missing clear specification of the type of reference they return type: behavior versions: Python 2.7 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14189> _______________________________________
Changes by Meador Inge <meadori@gmail.com>: ---------- nosy: +meador.inge _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14189> _______________________________________
Mark Lawrence added the comment: Can someone comment please as I'm not brave enough to touch the C code or docs. ---------- nosy: +BreamoreBoy _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14189> _______________________________________
Josh Rosenberg added the comment: If any of these actually return borrowed references, I'd consider it a serious documentation bug to not mention it. New reference semantics are the default, and while it's best to call them out, it can be assumed in most cases. Returning borrowed references without a big honking "not a normal function" flag in the docs causes a big problem. Heck, the lack of such a big warning flag on PyDict_Next (which doesn't return a PyObject, but populates via a double pointer) caused me a major headache recently when I DECREF-ed the resulting objects. Totally my fault (the description says they're borrowed), but I rely on that "Returns: Borrowed Reference" header so much that I made a dumb mistake. ---------- nosy: +josh.rosenberg _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14189> _______________________________________
Change by Mark Lawrence <breamoreboy@gmail.com>: ---------- nosy: -BreamoreBoy _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
Stéphane Wirtel <stephane@wirtel.be> added the comment: I would like to work on this issue. ---------- nosy: +matrixise versions: +Python 3.8 -Python 2.7 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
Serhiy Storchaka <storchaka+cpython@gmail.com> added the comment: This may be fixed recently (see issue18085, issue32077, issue35475 etc). Just check that this is true for all reported functions. ---------- nosy: +serhiy.storchaka _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
Change by STINNER Victor <vstinner@python.org>: ---------- components: +C API title: Documentation for some C APIs is missing clear specification of the type of reference they return -> C API documentation must document if returned object is a borrowed reference or strong reference versions: +Python 3.10 -Python 3.8 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
Change by Joannah Nanjekye <nanjekyejoannah@gmail.com>: ---------- nosy: +nanjekyejoannah _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
Irit Katriel <iritkatriel@yahoo.com> added the comment: This was fixed for all the functions listed by the OP, except a few that no longer exist AFAICT: Doc/c-api/import.rst: _PyImport_FindExtension Doc/c-api/import.rst: _PyImport_FixupExtension Doc/c-api/init.rst: PyEval_GetCallStats Doc/c-api/int.rst: PyInt_FromSize_t ---------- nosy: +iritkatriel resolution: -> fixed stage: -> resolved status: open -> closed _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue14189> _______________________________________
participants (9)
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Baruch Sterin -
Irit Katriel
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Joannah Nanjekye
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Josh Rosenberg
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Mark Lawrence
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Meador Inge
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Serhiy Storchaka
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STINNER Victor
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Stéphane Wirtel