[Python-Dev] Using logging in the stdlib and its unit tests (original) (raw)

skip at pobox.com skip at pobox.com
Wed Dec 8 20:14:25 CET 2010 

>> On a slightly tangential note, what do you think of the idea of
>> library code including info or debug level logging? In effect,
>> tracing and diagnostic code built in and available simply by changing
>> the logging level?

Vinay> That's how it works right now. You get info() and debug()
Vinay> messages sent via calls in library code, just by changing the
Vinay> level of (say) the root logger.

There can be performance implications if you log heavily. I don't know how the code is organized, but functionally these two calls are equivalent:

>>> logging.error("error 1 2 3 %s" % "yup")
ERROR:root:error 1 2 3 yup
>>> logging.error("error 1 2 3 %s", "yup")
ERROR:root:error 1 2 3 yup

The second form should be preferred in library code as long as the format string expansion is deferred until after the test is made to emit the message.

Skip

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