[code-quality] Namespaced packages and relative imports

[François Vanderkelen]

Hi Sylvain, experts.

I tried to work a little more on this and I found out why it "worked" with
setuptools 0.9.8.

Turns out it did not, it is just when you start with a clean environement
(not containing any of your namespaced packages) pylint is running properly
and flagging every import of related namespace packages as missing.

Although the good part is that it is matching properly relatives import,
you cannot have multiple dependencies to packages from the same namespace.

I am pretty sure that namespace usage is "erratic" in python since even
Setuptools does not seem to respect PEP420, but I am not sure the fact the
Pylint block on this comes from setuptools.

I think is is worth fixing but I am not sure where to start :)


2014-05-16 15:57 GMT+02:00 François Vanderkelen <
vanderkelen.francois at gmail.com>:

> I tried multiple things, first even if I install the package before
> running pylint it won't work except on one of my machines.
>
> So I tried to narrow it down with setuptools :
>
> Working with 0.9.8
> Not working with 2.2 (ImportError)
> Not working with 3.6 (ImportError)
>
> I guess setuptools changed something concerning namespaces packages, bug
> or not this is another story. I'll keep looking.
>
> Thanks a lot Sylvain
>
>
> 2014-05-16 15:01 GMT+02:00 Sylvain Thénault <sylvain.thenault at logilab.fr>:
>
> On 16 mai 14:42, François Vanderkelen wrote:
>> > Hi Sylvain,
>> >
>> > First of all thanks for the quick answer. I tried to create a dummy
>> project
>> > (the real one is confidential and not mine to give to the community)
>> and it
>> > helped me narrow down my two issues.
>> >
>> > The ImportError: No module named project is linked to the relative
>> import,
>> > and I could not reproduce the error in a dummy project. I finally found
>> it,
>> > it has to do with my namespaces packages.
>> >
>> > What I mean by namespaces is in my python library I dispose of several
>> > packages like this :
>> >
>> > company.mongodb
>> > company.redis
>> > company.hbase
>> >
>> > And also :
>> >
>> > company.project.core
>> > company.project.app.dashboard
>> > company.project.app.security
>> >
>> > Where company and project are all the same things, this allows me and my
>> > team to easily identify each package and what it is supposed to do. We
>> try
>> > to foster the open-source spirit in my company, hence the company
>> top-level
>> > namespace. It is still internal but at least we share it across all
>> teams :)
>> >
>> > Going back to the issue, if one package of the namespace is installed,
>> then
>> > apparently pylint is looking directly inside the python path and can't
>> find
>> > my package since it is not yet installed. I have the same issue with the
>> > "python setup.py develop" command, so I guess I am doing namespacing
>> wrong,
>> > or it is not well defined in python ?
>> >
>> > The only thing I do is adding
>> > *_import__('pkg_resources').declare_namespace(__name__)
>> > *in the __init__.py of the namespace package.
>> >
>> > If I run pylint in another environment without any packages installed,
>> it
>> > works like a charm (except I have a bunch of violations for missing
>> > imports).
>> >
>> > Do you want me to open an issue on bitbucket explaining all that or do
>> you
>> > think I am doing something I am not supposed to do ?
>>
>> I think what you're doing is right.
>>
>> The crash has already been supported:
>>
>> https://bitbucket.org/logilab/pylint/issue/203/importing-namespace-packages-crashes
>>
>> It seems to me that the namespace package issue is related to recent
>> version of
>> setuptools and has also been reported but can't find it right away.
>>
>> --
>> Sylvain Thénault, LOGILAB, Paris (01.45.32.03.12) - Toulouse
>> (05.62.17.16.42)
>> Formations Python, Debian, Méth. Agiles: http://www.logilab.fr/formations
>> Développement logiciel sur mesure:       http://www.logilab.fr/services
>> CubicWeb, the semantic web framework:    http://www.cubicweb.org
>>
>
>
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