[Distutils] Using Wheel with zipimport

[Paul Moore]

On 29 January 2014 05:52, Donald Stufft <donald at stufft.io> wrote:
> Which further shows that at the time it was "cool that it worked" but that
> the "weird failures" being a reason that Wheel was an installation format.

Having "cool" features in a format is not a bad thing. Zip imports are
the "cool " feature here - they have been used for lots of really
impressive things (like py2exe, for a less controversial example). But
they have limitations (which become "weird failures" when people try
to use the feature without knowing or catering for the limitations)
and it's the responsibility of the user to understand and address
those limitations - or not use the feature if the limitations are too
great for them.

> I believe that adding this "feature" to the PEP ex post facto is a bad idea.
> Had the  PEP contained anything to indicate that Wheels were intended
> to be importable as part of the design philosophy I would have spoken out
> about it then instead it's  been added after it was accepted with no
> discussion that I can see.

As I recall, it was in the original version of the PEP/spec and it was
always an intended feature. The wheel file for the wheel project
itself is (deliberately) runnable as a zip file, so that you can
bootstrap into the wheel world using the "wheel install" command.

I do *not* recommend using wheels as a runtime format if the package
in the wheel hits any of the limitations of zipimport (C extensions,
data files that are not or cannot be accessed via
pkgutil.package_data, etc). I also would not recommend using wheels
except in *very* specialised circumstances (where you have the wheel
already and cannot easily just install it before use - pip, ensurepip,
virtualenv and similar distribution-oriented environments are the key
use cases here). But I do think the feature is useful and should be
supported.

Paul.