Folks, After a huge delay, I finally found the time to implement the PEP 485 isclose() function, in C. I tihnk it's time for some review. I appologise for the fact that I have little experience with C, and haven't used the raw C API for years, but it's a pretty simple function, and there's lots of code to copy, so I think it's in OK shape. I hav not yet integrated it with the cPyton source code -- it belongs in mathmodule.c, but I found it easier to put it in a separate module while figuring it out.
You can find the code in the same gitHub repo as the draft PEP and python prototyping code: https://github.com/PythonCHB/close_pep the code is in: is_close_module.c There is a test module in: test_isclose_c.py and it can be built with: python3 setup.py build_ext --inplace Let me know if I should restructure it or put it anywhere else before it gets reviewed but in the meantime, i welcome any feedback. Thanks, -Chris A few questions I have off the bat: C-API (and plain C) questions: ============================= * Is there a better way to create a False or True than:: PyBool_FromLong(0) and PyBool_FromLong(1) * Style question: should I put brackets in an if clause that has only one line?:: if (some_check) { just_this_one_expression } * I can't find docs for PyDoc_STRVAR: but it looks like it should use it -- how? * I'm getting a warning in my PyMethodDef clause:: static PyMethodDef IsCloseMethods[] = { {"isclose", isclose_c, METH_VARARGS | METH_KEYWORDS, "determine if two floating point numbers are close"}, {NULL, NULL, 0, NULL} /* Sentinel */ }; is_close_module.c:61:17: warning: incompatible pointer types initializing 'PyCFunction' (aka 'PyObject *(*)(PyObject *, PyObject *)') with an expression of type 'PyObject *(PyObject *, PyObject *, PyObject *)' [-Wincompatible-pointer-types] {"isclose", isclose_c, METH_VARARGS | METH_KEYWORDS, but it seems to be working -- and I've copied, as well as I can, the examples. Functionality Questions: ======================== * What do do with other numeric types? - Integers cast fine... - Decimal and Fraction cast fine, too -- but precision is presumably lost. - Complex ? -- add it to cmath? * It's raising an Exception for negative tolerances: which don't make sense, but don't really cause harm either (fabs() is used anyway). I can't say I recall why I did that for the python prototype, but I reproduced in the C version. Should I? * What about zero tolerance? should equal values still be considered close? They are now, and tests reflect that. -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception [email protected]
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