[openstack-dev] HACKING and new-style relative imports
kispear at gmail.com
Wed Jul 10 05:13:28 UTC 2013
On 10 July 2013 02:31, Monty Taylor <mordred at inaugust.com> wrote:
> On 07/09/2013 10:55 AM, Joe Gordon wrote:
>> On Tue, Jul 9, 2013 at 1:28 PM, Kieran Spear <kispear at gmail.com
>> <mailto:kispear at gmail.com>> wrote:
>> Hi all,
>> There's a review up to make Horizon pass H304 (no relative imports):
>> Old-style relative imports are dangerous, but I can't think of a
>> good enough reason to forbid new-style imports, e.g.:
>> from .views import IndexView
>> instead of
>> from openstack_dashboard.dashboards.project.images_and_snapshots.views \
>> import IndexView
>> particularly in Horizon where nesting is deep and you otherwise end
>> up with many imports that won't fit into 80 characters. I think if
>> we're going to make the change above the benefits would need to
>> outweigh the effect on readability.
>> There's some discussion on the review already, but I'd like to hear
>> from a more general audience. Thoughts?
>> "Do not use relative names in imports. Even if the module is in the same
>> package, use the full package name. This helps prevent unintentionally
>> importing a package twice."
> From pep8:
> Relative imports for intra-package imports are highly discouraged.
> Always use the absolute package path for all imports. Even now that PEP
> 328 is fully implemented in Python 2.5, its style of explicit relative
> imports is actively discouraged; absolute imports are more portable and
> usually more readable.
In Horizon I think it's obvious that relative imports are more readable (and type-able) than the alternative. If portable is referring to moving code around, I think each style has portability benefits for both inter- and intra-package module moves, and there's a lot of overlap.
It sounds like this particular paragraph has been updated to account for PEP328 without considering why new-style imports should be discouraged.
There was a thread on python-dev a few years ago about the same issue:
On 10/5/2010 2:21 PM, Guido van Rossum wrote:
> On Tue, Oct 5, 2010 at 11:17 AM, Darren Dale<dsdale24 at gmail.com> wrote:
>> The issue is implementing a PEP with nice support for relative
>> imports, and then documenting that it should never be used.
> Isn't this mostly historical? Until the new relative-import syntax was
> implemented there were various problems with relative imports. The
> short-term solution was to recommend not using them. The long-term
> solution was to implement an unambiguous syntax. Now it is time to
> withdraw the anti-recommendation. Of course, without going overboard
> -- I still find them an acquired taste; but they have their place.
But nothing ever came of the bug:
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