I’m On 25. Aug 2018, at 00:13, Nathaniel Smith <njs@pobox.com> wrote:

On Fri, Aug 24, 2018 at 1:46 PM, Stephan Hoyer <shoyer@gmail.com> wrote:
On Fri, Aug 24, 2018 at 1:36 AM Hameer Abbasi <einstein.edison@gmail.com>

On Fri, Aug 24, 2018 at 9:38 AM Nathaniel Smith <njs@pobox.com> wrote:

On Thu, Aug 23, 2018 at 9:02 AM,  <einstein.edison@gmail.com> wrote:
I might add that most duck array authors are highly unlikely to be
to the Python space. We should just put a big warning there while
and that’ll be enough to scare away most devs from doing it by default.

That's a reasonable idea... a Big Obnoxious Warning(tm) when it's
enabled, or on first use, would achieve a lot of the same purpose.

if this_is_the_first_array_function_usage():
       "WARNING: this program uses NumPy's experimental
'__array_function__' feature.\n"
       "It may change or be removed without warning, which might
break this program.\n"
       "For details see


I was thinking of a FutureWarning... That's essentially what it's for.
Writing to stderr looks un-pythonic to me.

Issuing a FutureWarning seems roughly appropriate here. The Python 3.7 docs
"Base category for warnings about deprecated features when those warnings
are intended for end users of applications that are written in Python."

Writing to sys.stderr directly is generally considered poor practice for a
Python libraries.

In my experience FutureWarning does a good job of satisfying the goals of
being a "Big Obnoxious Warning" while still being silence-able and testable
with standard tools.

Yeah, the reason warnings are normally recommended is because
normally, you want to make it easy to silence. But this is the rare
case where I didn't want to make it easy to silence, so I didn't
suggest using a warning :-).

I really doubt anyone is going to silence a FutureWarning and then come complaining that a feature was removed.

Calling warnings.warn (or the C equivalent) is also very expensive,
even if the warning ultimately isn't displayed. I guess we could do
our own tracking of whether we've displayed the warning yet, and only
even attempt to issue it once, but that partially defeats the purpose
of using warnings in the first place.

How about calling it at enable-time once? That’s why I suggested that in the first place.


Nathaniel J. Smith -- https://vorpus.org
NumPy-Discussion mailing list

Best regards,
Hameer Abbasi
Sent from my iPhone