[Python-Dev] PEP 451 update

[Nick Coghlan]

On 24 October 2013 16:05, Eric Snow <ericsnowcurrently at gmail.com> wrote:
> I've had some offline discussion with Brett and Nick about PEP 451
> which has led to some meaningful clarifications in the PEP.  In the
> interest of pulling further discussions back onto this
> (archived/public) list, here's an update of what we'd discussed and
> where things are at. :)

There's also the fact Guido asked Brett and I to be co-delegates for
this PEP, and we accepted (we both already agree with the overall
concept, so it's just a matter of hammering out the final API
details).

> * path entry finders indicate that they found part of a possible
> namespace package by returning a spec with no loader set (but with
> submodule_search_locations set).  Brett wanted some clarification on
> this.
> * The name/path signature and attributes of file-based finders in
> importlib will no longer be changing.  Brett had some suggestions on
> the proposed change and it became clear that the the change was
> actually pointless.
> * I've asserted that there shouldn't be much difficulty in adjusting
> pkgutil and other modules to work with ModuleSpec.

More specifically: importlib finders will still expose the previous
import plugin API for backwards compatibility, so the worst case
scenario is that we miss something and there's an API somewhere that
doesn't accept import plugins that only provide the new API and not
the old one.

However, the PEP should explicitly state that any such omissions will
be treated as bugs in the 3.4.x series (although we'll aim to handle
them all in the initial implementation).

Thanks for recording the details of the earlier off-list discussion :)

Cheers,
Nick.

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