Re: PyGObject (3.4.0) - importing overrides modules from different directories

[Lukas Vacek <lucas vacek gmail com>]

Simon,

I see you had ran into the problem with extend_path and code in
__init__.py already (comment 26 in the bug report you posted earlier).
Do you think it is a good practice for pygobject overrides module
developers to create a symlink from __init__.py in their installed
module to __init__.py in pygobject overrides/ directory?

Lukas

On Fri, Oct 26, 2012 at 1:25 PM, Lukas Vacek <lucas vacek gmail com> wrote:
> Hey Simon,
>
> Thanks for pointing me to the bug report. Yes, it is possible to load
> overrides from different paths already. This goes a bit further and
> allows loading overrides from different paths no matter the order of
> sys.path.
>
> Let's have a look at gst-python as it is the subject of the bug
> report: if you run PYTHONPATH=path-to-gst-python python -c "import gi;
> print(str(dir(gi)))" you can see gi module wasn't loaded properly.
> That's because __init__.py in pygobject overrides contains other code
> than just calling extend_path from pkgutil. Indeed you can use
> PYTHONPATH=path-to-pygobject:path-to-gst-python and all is good.
>
> This might seem like a trivial issue. Well, it's nothing major, but it
> causes confusion - for example, the two issues in pitivi I linked in
> my first email stems from this.
>
> Cheers,
> Lukas
>
> On Fri, Oct 26, 2012 at 12:53 PM, Simon Feltman <s feltman gmail com> wrote:
>> Hi Lukas,
>>
>> You should already be able to use overrides in different paths
>> searchable by python (anything that shows up in sys.path). The trick
>> is you need to use pkgutil within each of the __init__.py files within
>> your custom gi/overrides folders. There are more details which may be
>> a helpful in this bug report:
>> https://bugzilla.gnome.org/show_bug.cgi?id=680913
>>
>> -Simon
>>
>> On Fri, Oct 26, 2012 at 4:23 AM, Lukas Vacek <lucas vacek gmail com> wrote:
>>> I see the last mail didn't catch much attention. Anyway, I have come
>>> up with two possible solutions to the problem.
>>>
>>> 1) Use imp instead of __import__
>>> Just look for a file "gi/overrides/Module_name.py" in sys.path and
>>> don't worry about __init__.py (overrides module can't use __init__.py
>>> anyway as they clash with pygobject's overrides' init which is the
>>> root cause of the whole problem), then load it with imp. It feels a
>>> bit untidy but works fine. This is the attached
>>> pygobject-3.4.0-overrides-load-py-files-instead-of-modules.patch.
>>> Indeed this should look for other supported suffixes than .py as well.
>>>
>>> 2) Ask overrides module developers to symlink __init__.py
>>> This solution feels cleaner and requires no changes to existing
>>> pygobject code. The solution is to link __init__.py from overrides
>>> modules to system pygobject overrides directory in case overrides
>>> module is installed outside of pygobject tree. With autotools, this
>>> can be done easily by using install-exec-hook -
>>> gst-python-symlink-__init__.py-to-system-gi-overrides-on-install.patch
>>> demonstrates this idea on gst-python.
>>>
>>> Cheers,
>>> Lukas Vacek
>>>
>>> On Mon, Oct 22, 2012 at 1:35 PM, Lukas Vacek <lucas vacek gmail com> wrote:
>>>> Hi All,
>>>>
>>>> I have found out it's not possible to load installed GI overrides from
>>>> a different directory than where PyGObject itself is installed
>>>> (/usr/lib/python2.7/dist-packages/ in my case).
>>>>
>>>> Ideally gi overrides modules could be installed to user site-packages
>>>> directory and still would be loaded by system installation of
>>>> PyGObject.
>>>>
>>>> The problem is that the overrides module can't install __init__.py
>>>> file because it would conflict with __init__.py already installed by
>>>> system PyGObject. (Or even if the file was not installed in the same
>>>> location but the installed overrides module (with own __init__.py)
>>>> would appear before system PyGObject in sys.path it would be loaded
>>>> instead of PyGObject as gi module and break things. )
>>>>
>>>> However, __init__.py must be present in the gi overrides module
>>>> directory in order to be recognized by __import__ call made by
>>>> PyGObject when loading overrides module (module.py around line 244).
>>>>
>>>> This makes it complicated to use gi overrides module from a different
>>>> directory. The workaround is to load _uninstalled_ gi overrides
>>>> modules with PYTHONPATH which explicitly mentions PyGObject path
>>>> before the path to overrides modules. For example, this is how I run
>>>> pitivi: PYTHONPATH=/usr/lib/python2.7/dist-packages/:~/dev/gst-python/
>>>> python bin/pitivi
>>>>
>>>> Pitivi bugs https://bugzilla.gnome.org/show_bug.cgi?id=686341 and
>>>> https://bugzilla.gnome.org/show_bug.cgi?id=686342 seem to be related
>>>> to/caused by this.
>>>>
>>>> To solve this pygobject might look for a ".py" file instead of a module.
>>>>
>>>> Thanks!
>>>> Lukas Vacek
>>>
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