[Python-Dev] --with-fpectl changes the CPython ABI

Nick Coghlan ncoghlan at gmail.com
Sun Dec 25 20:55:04 EST 2016

On 25 December 2016 at 09:48, Nathaniel Smith <njs at pobox.com> wrote:

> Or maybe make it so that even no-fpectl builds still export the
> necessary symbols so that yes-fpectl extensions don't crash on import?
> (This has the advantage that it can be done in a point release...)

This seems like a sensible thing to do in 3.6, 3.5 and 2.7 regardless of
what happens in 3.7.

For 3.7, I don't understand the trade-offs well enough to have a strong
opinion, but dropping the feature entirely does seem reasonable - folks
that want fine-grained floating point exception control these days are
likely to be much better served by the decimal module, or one of the third
party computing libraries (numpy, gmpy, sympy, etc).

There was a thread back in 2012 [1] regarding the possibility of instead
updating floats to offer flexibility similar to that offered by those other
modules, but I think our discussions of the expected semantics of a decimal
literal show that that would be a bad idea - context dependent behaviour in
numeric literals creates all sorts of problems at the level of compiler and
interpreter design.


[1] https://mail.python.org/pipermail/python-ideas/2012-October/016768.html

Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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