[Numpy-discussion] tighten up ufunc casting rule

[Mark Wiebe]

On Thu, Jun 2, 2011 at 3:09 PM, Gael Varoquaux <
gael.varoquaux at normalesup.org> wrote:

> On Thu, Jun 02, 2011 at 03:06:58PM -0500, Mark Wiebe wrote:
> >    Would anyone object to, at least temporarily, tightening up the
> default
> >    ufunc casting rule to 'same_kind' in NumPy master? It's a one line
> change,
> >    so would be easy to undo, but such a change is very desirable in my
> >    opinion.
> >    This would raise an exception, since it's np.add(a, 1.9, out=a),
> >    converting a float to an int:
>
> >    >>> a = np.arange(3, dtype=np.int32)
>
> >    >>> a += 1.9
>
> That's probably going to break a huge amount of code which relies on the
> current behavior.
>
> Am I right in believing that this should only be considered for a major
> release of numpy, say numpy 2.0?


Absolutely, and that's why I'm proposing to do it in master now, fairly
early in a development cycle, so we can evaluate its effects. If the next
version is 1.7, we probably would roll it back for release (a 1 line
change), and if the next version is 2.0, we probably would keep it in.

I suspect at least some of the code relying on the current behavior may have
bugs, and tightening this up is a way to reveal them.

-Mark


>
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