[Python-ideas] Changing the meaning of bool.__invert__

[Ian Kelly]

On Sat, Apr 9, 2016 at 9:25 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Sat, Apr 09, 2016 at 08:28:10AM -0600, Ian Kelly wrote:
>
>> It seems unusual to deprecate something without also providing a means
>> of using the new thing in the same release. "Don't use this feature
>> because we're going to change what it does in the future. Oh, you want
>> to use the new version? Psych! We haven't actually done anything yet.
>> Use not instead." It creates a weird void in Python 3.6 where the
>> operator still exists but absolutely nobody has a legitimate reason to
>> be using it.
>
> Not really. This is quite similar to what happened in Python 2.3 during
> int/long unification. The behaviour of certain integer operations
> changed, including the meaning of some literals, and warnings were
> displayed.

Pointing out that this has been done once before, 11 minor releases
prior, does not dissuade me from continuing to characterize it as
"unusual". The int/long unification was also a much more visible
change overall.

>> What happens if somebody is using ~ for its current semantics, skips
>> the 3.6 release in their upgrade path, and doesn't read the release
>> notes carefully enough? They'll never see the warning and will just
>> experience a silent and difficult-to-diagnose breakage.
>
> Then they'll be in the same position as everybody if there's no
> depreciation at all.

I'm not suggesting there should be no deprecation. I'm just
questioning whether the proposed deprecation is sufficient.