mirror of https://github.com/python/cpython
Added clarification to logging HOWTO.
This commit is contained in:
parent
64cca12622
commit
b322621a53
|
@ -738,12 +738,11 @@ Configuring Logging for a Library
|
|||
When developing a library which uses logging, you should take care to
|
||||
document how the library uses logging - for example, the names of loggers
|
||||
used. Some consideration also needs to be given to its logging configuration.
|
||||
If the using application does not use logging, and library code makes logging
|
||||
calls, then (as described in the previous section) events of severity
|
||||
``WARNING`` and greater will be printed to ``sys.stderr``. This is regarded as
|
||||
the best default behaviour.
|
||||
If the using application does not configure logging, and library code makes
|
||||
logging calls, then (as described in the previous section) an error message
|
||||
will be printed to ``sys.stderr``.
|
||||
|
||||
If for some reason you *don't* want these messages printed in the absence of
|
||||
If for some reason you *don't* want this message printed in the absence of
|
||||
any logging configuration, you can attach a do-nothing handler to the top-level
|
||||
logger for your library. This avoids the message being printed, since a handler
|
||||
will be always be found for the library's events: it just doesn't produce any
|
||||
|
@ -755,7 +754,7 @@ handlers, as normal.
|
|||
A do-nothing handler is included in the logging package:
|
||||
:class:`~logging.NullHandler` (since Python 2.7). An instance of this handler
|
||||
could be added to the top-level logger of the logging namespace used by the
|
||||
library (*if* you want to prevent your library's logged events being output to
|
||||
library (*if* you want to prevent an error message being output to
|
||||
``sys.stderr`` in the absence of logging configuration). If all logging by a
|
||||
library *foo* is done using loggers with names matching 'foo.x', 'foo.x.y',
|
||||
etc. then the code::
|
||||
|
|
Loading…
Reference in New Issue