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Make PyComplex_RealAsDouble/ImagAsDouble use __complex__ #109598
Description
The C-API docs says: "Return the real/imag part of op as a C double." But the real code looks like:
PyComplex_RealAsDouble(PyObject *op)
{
if (PyComplex_Check(op)) {
return ((PyComplexObject *)op)->cval.real;
}
else {
return PyFloat_AsDouble(op);
}
}So, we assume instead that the op is a float-like class (a subtype of or something with a __float__ dunder method). Instead, we should look on the __complex__ method in the else branch. This is an issue like #44670, I think.
Minor issue: these functions aren't tested, only indirectly with format() (that will not trigger all possible cases).
Edit:
The current PyComplex_ImagAsDouble() silently returns 0.0 for all non-PyComplexObject objects (or subtypes of). I think it's a bug and we should return -1.0 instead and set the error indicator.
Activity
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
skirpichev commentedon Nov 5, 2023
PR is ready for review: #109647
gh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __complex__ (G…
encukou commentedon Jan 15, 2024
Thanks for the PR!
I don't think this is bugfix-y enough to need backporting.
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…
pythongh-109598: make PyComplex_RealAsDouble/ImagAsDouble use __compl…