pyudev.glib incompatible with Python 3

[Arfrever]

$ python2.7 -c 'import pyudev.glib'
$ python3.2 -c 'import pyudev.glib'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python3.2/site-packages/pyudev/glib.py", line 40, in <module>
    from . import glib
ImportError: cannot import name glib

I use pygobject-2.28.6 with some patches backported from pygobject repository. This version of pygobject has been separately built and installed for each version of Python.

2to3 changed 'import glib' into 'from . import glib' during processing of pyudev/glib.py.
If I manually revert this change, then the following error occurs:

$ python3.2 -c 'import pyudev.glib'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python3.2/site-packages/pyudev/glib.py", line 45, in <module>
    class GUDevMonitorObserver(gobject.GObject):
  File "/usr/lib64/python3.2/site-packages/gobject/__init__.py", line 60, in __init__
    cls._type_register(cls.__dict__)
  File "/usr/lib64/python3.2/site-packages/gobject/__init__.py", line 115, in _type_register
    type_register(cls, namespace.get('__gtype_name__'))
TypeError: __gsignals__ keys must be strings

[swsnr]

glib support isn't tested against Python 3, because I didn't know that pygobject already supports Python 3.

Do you know which version (unpatched of course) of pygobject introduced Python 3 support?

[Arfrever]

Released versions don't yet contain these patches:
http://git.gnome.org/browse/pygobject/commit/?id=4e5833d0c2fe548617e5ea510f05920fd0caf73b
http://git.gnome.org/browse/pygobject/commit/?id=426c7109d4c0dbf0d56cc075f97f33b3451f79a8
http://git.gnome.org/browse/pygobject/commit/?id=9ae43fdbcc547eb1e3c61bf9545da40555b2e2c6
http://git.gnome.org/browse/pygobject/commit/?id=8f89ff24fcac627ce15ca93038711fded1a7c5ed
http://git.gnome.org/browse/pygobject/commit/?id=2940d0c45c592c19196d4ab0d345ab27fca0f0a0

[swsnr]

So there is no released version with Python 3 support yet? In this case, you are on your own for now. I'm not using the glib module myself, and thus need the unit tests to make sure that the glib module works. The unit tests don't run with checkouts from git, but with released versions, and I simply lack the time to adapt the test toolchain to support tests against a git clone of pygobject. I'm sorry.

I don't see any reason to support something that isn't even released yet anyway. Closing as invalid for now, please re-open, if I'm mistaken and there is a released pygobject version with Python 3, or if a new pygobject release provides Python 3 support. Of course, if you can provide patches for pyudev.glib to add Python 3 support, I'll gladly accept these and commit them,as long as they are covered by tests.

[Arfrever]

This patch avoid problem during importing:

--- pyudev/glib.py
+++ pyudev/glib.py
@@ -35,9 +35,7 @@
 from __future__ import (print_function, division, unicode_literals,
                         absolute_import)

-# thanks to absolute imports, this really imports the glib binding and not this
-# module again
-import glib
+glib = __import__("glib")
 import gobject


@@ -64,16 +62,16 @@

     __gsignals__ = {
         # glib apparently expects byte-strings as signal names
-        b'device-event': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_STRING, gobject.TYPE_PYOBJECT)),
-        b'device-added': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_PYOBJECT,)),
-        b'device-removed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                            (gobject.TYPE_PYOBJECT,)),
-        b'device-changed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                            (gobject.TYPE_PYOBJECT,)),
-        b'device-moved': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_PYOBJECT,)),
+        'device-event': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_STRING, gobject.TYPE_PYOBJECT)),
+        'device-added': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_PYOBJECT,)),
+        'device-removed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                           (gobject.TYPE_PYOBJECT,)),
+        'device-changed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                           (gobject.TYPE_PYOBJECT,)),
+        'device-moved': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_PYOBJECT,)),
         }

     def __init__(self, monitor):

[Arfrever]

Already existing tests for pyudev.glib in tests/test_observer.py pass with this patch applied.

[swsnr]

I doubt that the patch passes tests on Python 2. Did you try that?

And please don't use __import__ for importing regular modules. Fix the import by using a proper relative or absolute import.

[Arfrever]

setup.py uses 2to3, which changes 'import glib' into 'from . import glib'. How do you suggest to fix it?

[Arfrever]

This patch works with Python 2 and 3:

--- pyudev/glib.py
+++ pyudev/glib.py
@@ -32,12 +32,9 @@
 """


-from __future__ import (print_function, division, unicode_literals,
-                        absolute_import)
+from __future__ import print_function

-# thanks to absolute imports, this really imports the glib binding and not this
-# module again
-import glib
+glib = __import__("glib")
 import gobject


@@ -63,17 +60,16 @@
         'change': 'device-changed', 'move': 'device-moved'}

     __gsignals__ = {
-        # glib apparently expects byte-strings as signal names
-        b'device-event': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_STRING, gobject.TYPE_PYOBJECT)),
-        b'device-added': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_PYOBJECT,)),
-        b'device-removed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                            (gobject.TYPE_PYOBJECT,)),
-        b'device-changed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                            (gobject.TYPE_PYOBJECT,)),
-        b'device-moved': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
-                          (gobject.TYPE_PYOBJECT,)),
+        'device-event': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_STRING, gobject.TYPE_PYOBJECT)),
+        'device-added': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_PYOBJECT,)),
+        'device-removed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                           (gobject.TYPE_PYOBJECT,)),
+        'device-changed': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                           (gobject.TYPE_PYOBJECT,)),
+        'device-moved': (gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE,
+                         (gobject.TYPE_PYOBJECT,)),
         }

     def __init__(self, monitor):

[swsnr]

I managed to get pygobject building against Python 3, so now I'm able to run the pyudev.glib tests with Python 3. The bug is indeed very valid, sorry for all the hassle. I'll take care for this issue asap, I just need to figure out the best way to fix the glitches. The import is the biggest problem. In theory it is written to support python 2 and python 3, but unfortunately 2to3 fails to handle such imports correctly (an upstream bug in python). I'll probably have to adjust the 2to3 fixers used to generate the Python 3 code.

[Arfrever]

Python issue #8358 was already fixed in Python version used by me.
I have filed Python issue #12873.

[swsnr]

I already had doubts about #8358 myself, because it's marked fixed since over a year ago. But I didn't investigate the cause of this issue further, because it was obviously solved by disabling the import fixer. Thanks for doing so yourself. Luckily #12873 didn't hit pyudev at other places, multiline future imports are used in every pyudev module.

[swsnr]

And just for the record: Yesterday I released pyudev 0.12 which fixes this issue.