Feature or enhancement

Proposal:

Currently there is only a slow way (i.e.PyNumber_Negative()) to invert the sign of a big integer. Direct manipulation of the sign value is available only via private function, e.g._PyLong_SetSignAndDigitCount():
https://github.com/aleaxit/gmpy/blob/1c0d4f38d4f1093df0e9460d82e4331d3d3946b6/src/gmpy2_convert_gmp.c#L153

I propose this interface:

intPyLong_FlipSign(PyObject*obj);

For small integers it will fallback toPyLong_FromLong() (like_PyLong_Negate() does), for the rest - just_PyLong_FlipSign() to change sign in place.

Alternatively, we could just expose a direct wrapper of_PyLong_FlipSign() and warn users to not use this function for small ints (that doesn't make sense for me anyway).

In both variants, on success - flip the sign ofobj and return 0. On failure - return -1 with exception set. Shouldn't fail on PyLongObject or it's subtype.

I'll work on a patch if this proposal does make sense.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-120446: add PyLong_FlipSign() public function #120489