Installing python __init__.py file from multiple KF5 frameworks

[Elvis Stansvik]

> In data giovedì 19 maggio 2016 19:00:07 CEST, Stephen Kelly ha scritto:
>
>> have to be changed for the namespaced module stuff?
>
> Sorry, you were perfectly clear. It was me who didn't get the request. ;)
>
>>  SOME_PYTHON_2_LOCATION/PyKF5/__init__.py
>>  SOME_PYTHON_2_LOCATION/PyKF5/KWidgetsAddons.so
>>  SOME_PYTHON_2_LOCATION/PyKF5/KItemModels.so
>>  SOME_PYTHON_3_LOCATION/PyKF5/__init__.py
>>  SOME_PYTHON_3_LOCATION/PyKF5/KWidgetsAddons.so
>>  SOME_PYTHON_3_LOCATION/PyKF5/KItemModels.so
>
> Each subpackage should have its own sub-directory with an __init__.py
> importing its contents, e.g:.
>
> SOME_PYTHON_3_LOCATION/PyKF5/KWidgetAddons/__init__.py
> SOME_PYTHON_3_LOCATION/PyKF5/KWidgetsAddons/KWidgetsAddons.so
>
> Then, 2 different cases depending if you use Python 3 or 2.
>
> Python 3: the final result should look like
>
> SOME_PYTHON_3_LOCATION/PyKF5/
> SOME_PYTHON_3_LOCATION/PyKF5/KWidgetAddons/__init__.py
> SOME_PYTHON_3_LOCATION/PyKF5/KWidgetsAddons/KWidgetsAddons.so
>
> Python 2:
>
> SOME_PYTHON_2_LOCATION/PyKF5/__init__.py
> SOME_PYTHON_2_LOCATION/PyKF5/KWidgetAddons/__init__.py
> SOME_PYTHON_2_LOCATION/PyKF5/KWidgetsAddons/KWidgetsAddons.so
>
> The __init__.py should contain only
>
> from pkgutil import extend_path
> __path__ = extend_path(__path__, __name__)
>
> This will fix it from the Python side. With regards to the __init__.py,

First of all: A big thanks to Shaheed and Steve for digging down on this!

Now, I understand that if you want to reap the benefits of using PEP
420 implicit namespace packages on Python 3, you have to use the
nested structure described by Luca above, since namespace packages may
not contain any modules, only subpackages.

However, speaking as a Python user, consider the consequence of this
for the import statements in Python. With the first approach (the .so
modules directly in the KF5 package), I can do e.g:

import KF5.KItemModels

or say

from KF5.KItemModels import KSelectionProxyModel

if I want to be a little more specific. Very similar to what I do in
PyQt (e.g. from PyQt5.QtCore import QObject).

With the second approach, where each module nested in a subpackage, I
would instead have to use the much longer and more repetitive

import KF5.KItemModels.KItemModels

or

from KF5.KItemModels.KItemModels import KSelectionProxyModel

I would therefore ask you to consider using the first approach, even
if implicit namespace packages may seem like the "right" solution here
(for Python 3) that is, and instead kindly ask packagers to take on
the burden of sorting out the conflicting __init__.py files, for the
added usability benefits.

It seems that at least in Debian, the issue has already come up [1],
although I don't know what solution is currently in place. I would
suspect other distros have also found ways to work around this
problem? (Zope..?)

If the KF5 bindings had installed a whole bunch of .so files in each
subpackage, it would be less of an issue I think, since then the
subpackages would give a natural grouping. But as I understand it, it
would essentially be a subdirectory for each framework, each
containing a single .so ? Then there's much less motivation for the
subpackage, from a user POV.

Again, many thanks for bringing bindings to KF5. Can't wait to try them out!

Best regards,
Elvis Stansvik

[1] https://wiki.debian.org/DebianPython/Namespaces