I know pyusb (in svn) is currently not really supported/ready but I have a
usability question/observation.
If I have a (dumb) example script that uses the "basic" logging settings and
pyusb fails to load a backend the OpenUSB load attempt ends up being logged
when it too fails, a traceback is also dumped (the script keeps on going).
Example script and output
## -------------------- cut here --
"""List usb devices using basic logging.
This shows conflicts with pyusb logging implementation.
"""
import logging
do_logging = True # And demo problem
#do_logging = False # Pick one :)
log = logging
if do_logging:
log.info('hello from test app, no more logging wil be issued form this
script')
import usb.core
import usb.util
import usb.backend.libusb10
# Monkey patch libusb10 away, or simply run on a machine without libusb10
def fake_get():
return None
usb.backend.libusb10.get_backend = fake_get
for dev in usb.core.find(find_all=True):
print dev
## -------------------- cut here --
## -------------------- cut here --
ERROR:usb.backend.openusb:Error loading OpenUSB backend
Traceback (most recent call last):
File "/home/clach04/dev/python/usb/pyusb/trunk/usb/backend/openusb.py",
line 598, in get_backend
_lib = _load_library()
File "/home/clach04/dev/python/usb/pyusb/trunk/usb/backend/openusb.py",
line 148, in _load_library
raise OSError('USB library could not be found')
OSError: USB library could not be found
<usb.core.Device object at 0x9d4f84c>
<usb.core.Device object at 0x9d4f8cc>
<usb.core.Device object at 0x9d4f92c>
<usb.core.Device object at 0x9d4f96c>
<usb.core.Device object at 0x9d4f9ac>
<usb.core.Device object at 0x9d4f9ec>
<usb.core.Device object at 0x9d4fa2c>
<usb.core.Device object at 0x9d4fa6c>
## -------------------- cut here --
is there a way to disable this behavior? I'm guessing this is some debug
code that is causing this. There are 2 issues:
1) the back trace that gets dumped out
2) the error gets logged (without logging for the usb.backend.openusb logger
being (explictly) turned on by the caller.
#2 is probably fixable by explicitly setting a log level (of off) in the
pyusb code. I could look into doing that if it would be helpful.
The workarounds are:
1) Don't use the basic logger in a user script, e.g. add something like; log
= logging.getLogger('mylogger') to the user script
2) use libusb10
It isn't a huge issue but a little odd.
Thanks!
Chris
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