getLevelName is missing a part of the behavior

[alexprengere]

logging.getLevelName works as a two way street between level and level names:

>>> import logging
>>> logging.getLevelName(logging.WARNING)
'WARNING'
>>> logging.getLevelName("WARNING")
30

In picologging, the second way raises a TypeError:

>>> logging.getLevelName("WARNING")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: level must be an integer

[aminalaee]

I agree that for the sake of backwards compatibility this should be modified,
but is there a specific use-case for it or just to be on par with logging?
It's really a weird behaviour.

[alexprengere]

I have used it in a private codebase to convert a logging level as a str to the corresponding int, so roughly:

import logging
import argparse

parser = argparse.ArgumentParser()
parser.add_argument("logging-level", default="DEBUG")
...
args = parser.parse_args()

level = logging.getLevelName(args.logging_level)
logging.basicConfig(..., level=level)

There are other ways to implement this (with their own problems..):

• level = getattr(logging, args.logging_level)
• level = logging._nameToLevel[args.logging_level]

I totally agree that this behavior of logging.getLevelName is out of place, and should be under its own function logging.getLevelFromName or so. The docs mention it too:

Changed in version 3.4: In Python versions earlier than 3.4, this function could also be passed a text level, and would return the corresponding numeric value of the level. This undocumented behaviour was considered a mistake, and was removed in Python 3.4, but reinstated in 3.4.2 due to retain backward compatibility.

[aminalaee]

Yeah I agree, seems like it shiuld be just kept for backwards conpatibility.