Jonathan Underwood <jonathan.underw...@gmail.com> added the comment:
Py_SIZE is actually precisely specified and documented[1] as it stands; I don't think a change there is needed. The usage I outlined is in line with that documentation, and many other uses of that macro in the cpython sources. The documentation issues are, at least: 1. There is no documentation specifying that bytes objects should be null terminated. 2. Nothing in the documentation of PyBytes_FromStringAndSize[2] specifies that passing 0 as the size results in a singleton being returned. This is undocumented behaviour, and it would seem fragile to rely on this. But there are more implementation inconsistencies: the documentation for PyBytes_AsString()[3] returns a buffer which is one byte longer than the length of the object *in order to store a terminating null*, which implies that the object need not itself have a terminating null. I could go on with other examples, but this is very poorly defined behaviour. Question: are bytes objects defined to be null terminated, or not? Because if they're not defined to be null terminated, the fix I propose is correct even if it doesn't solve the other 100 bugs lurking in the code. [Aside: even if bytes objects are in fact defined to be null terminated, I think the change proposed amounts to an optimization in any case.] [1] https://docs.python.org/3/c-api/structures.html#c.Py_SIZE [2] https://docs.python.org/3/c-api/bytes.html?highlight=pybytes_fromstringandsize#c.PyBytes_FromStringAndSize [3] https://docs.python.org/3/c-api/bytes.html?highlight=pybytes_asstring#c.PyBytes_AsString ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue32431> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
