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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>

wrote:

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

newcomers

to the Python space. We should just put a big warning there while

enabling

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.

E.g.

if this\_is\_the\_first\_array\_function\_usage():

sys.stderr.write(

"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

http://www.numpy.org/neps/nep-0018-array-function-protocol.html\\n"

)

-n

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

write:

"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 :-).

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.

-n

--
Nathaniel J. Smith -- https://vorpus.org
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