[Distutils] Using Wheel with zipimport

[Nick Coghlan]

On 29 January 2014 23:16, Donald Stufft <donald at stufft.io> wrote:
> So basically even though the text of the PEP specifically points out that a difference
> of Wheel and Egg is that Eggs are importable it somehow supports that? Can you
> point to a single line in the PEP that supports this besides the ones you've added?

I added the clarification based on the facts that:

1. We discussed this extensively before PEP 427 was approved, and this
was an accepted feature of the design
2. Root-is-purelib only makes sense in the context of supporting the feature
3. Both ensurepip and virtualenv rely on the feature
4. PEP 453 explicitly documents ensurepip's reliance on the feature,
with no caveat about this being unsupported in the spec
5. I wouldn't have accepted PEP 427 if wheels didn't provide a strict
superset of the features provided by eggs

We make mistakes, and things that were discussed and agreed don't
always get properly captured in the corresponding PEPs.

When that happens, it's a judgement call as to whether properly
documenting that is a new feature requiring a new PEP, or merely a
clarification to the existing one. For standard library PEPs, we often
don't do either - we just fix the implementation without going back
for another round of PEP discussions (for smaller tweaks, sometimes we
don't even go back to python-dev and instead just resolve things on
the tracker).

In this case, as BDFL-Delegate, I decided it was a case that merely
called for clarification, because I *know* what spec I accepted, and
it was the one where wheels offer all the features that eggs do and
more. I added the new text specifically because people like Armin
Ronacher and yourself had gained an idea from the PEP text that
emphatically does *not* align with the design discussions that
occurred prior to the acceptance of the PEP.

Now, if you'd like to campaign to *remove* this support, then explain
your rationale, and make the case for why you think providing the
feature is so dangerous that removing it is worth breaking backwards
compatibility over.

Regards,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia