[Python-Dev] PEP 520: Preserving Class Attribute Definition Order (round 5)

[Armin Rigo]

Hi,

On 24 June 2016 at 23:52, Eric Snow <ericsnowcurrently at gmail.com> wrote:
> Pending feedback, the impact on Python implementations is expected to
> be minimal.  If a Python implementation cannot support switching to
> `OrderedDict``-by-default then it can always set ``__definition_order__``
> to ``None``.

That's wishful thinking.  Any Python implementation that sets
``__definition_order__`` to None where CPython sets it to something
useful is likely going to break programs and be deemed not fully
compatible.  (Note: this PEP is not a problem for PyPy.)


A bientôt,

Armin.