[Python-Dev] PEP 451 update (original) (raw)

Brett Cannon brett at python.org
Sat Nov 2 16:21:39 CET 2013

On Sat, Nov 2, 2013 at 5:46 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:

On 2 November 2013 08:44, Eric Snow <ericsnowcurrently at gmail.com> wrote: > On Fri, Nov 1, 2013 at 11:59 AM, Brett Cannon <brett at python.org> wrote: >> Thanks for the clarification. It all SGTM. > > I've updated the PEP and the reference implementation.

While I was saying loader when I should have been saying finder, Eric correctly divined my intent :) > If I've missed > anything please let me know. There is only one thing I thought of > that I'd like to get an opinion on: > > In the Finders section, the PEP specifies returning None (or using a > different loader) when the found loader does not support loading into > an existing module (e.g during reload). An alternative to returning > None would be for the finder to raise ImportError with a message like > "the loader does not support reloading the module". This may actually > be a better approach since "could not find a loader" and "the found > loader won't work" are different situations that a single return value > (None) may not sufficiently represent. Throwing ImportError for "can load, but cannot load into that target module" sounds good to me.

SGTM as well.

We should also be explicit that throwing an exception from findspec stops the search (unlike returning None).

I thought that was obvious but more docs doesn't hurt. =)

> Other than that, I'm not aware of any blockers for the PEP. The one slight quibble I have with the PEP update is the wording regarding the "existing" parameter. I think runpy should pass the new parameter as well when calling findspec, but in that case it won't be an existing copy of the named module, it will be sys.modules["main"]. So we shouldn't set an expectation that the existing module passed in will necessarily be a previous copy of the module being loaded, it's just an indication to the finder that the target namespace for execution will be a pre-existing module rather than a new one. For the same reason, I also have a mild preference for "target" (or the more explicit "loadtarget") as the name, although I won't object if you and Brett prefer "existing".

I would go with "module" or "target" and that is where I shall end the bikeshedding. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20131102/4f507217/attachment.html>

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