class logging.Logger  
 
propagate  
If this attribute evaluates to true, events logged to this logger will be passed to the handlers of higher level (ancestor) loggers, in addition to any handlers attached to this logger. Messages are passed directly to the ancestor loggers’ handlers - neither the level nor filters of the ancestor loggers in question are considered. If this evaluates to false, logging messages are not passed to the handlers of ancestor loggers. The constructor sets this attribute to True.  Note If you attach a handler to a logger and one or more of its ancestors, it may emit the same record multiple times. In general, you should not need to attach a handler to more than one logger - if you just attach it to the appropriate logger which is highest in the logger hierarchy, then it will see all events logged by all descendant loggers, provided that their propagate setting is left set to True. A common scenario is to attach handlers only to the root logger, and to let propagation take care of the rest.  
  
setLevel(level)  
Sets the threshold for this logger to level. Logging messages which are less severe than level will be ignored; logging messages which have severity level or higher will be emitted by whichever handler or handlers service this logger, unless a handler’s level has been set to a higher severity level than level. When a logger is created, the level is set to NOTSET (which causes all messages to be processed when the logger is the root logger, or delegation to the parent when the logger is a non-root logger). Note that the root logger is created with level WARNING. The term ‘delegation to the parent’ means that if a logger has a level of NOTSET, its chain of ancestor loggers is traversed until either an ancestor with a level other than NOTSET is found, or the root is reached. If an ancestor is found with a level other than NOTSET, then that ancestor’s level is treated as the effective level of the logger where the ancestor search began, and is used to determine how a logging event is handled. If the root is reached, and it has a level of NOTSET, then all messages will be processed. Otherwise, the root’s level will be used as the effective level. See Logging Levels for a list of levels.  Changed in version 3.2: The level parameter now accepts a string representation of the level such as ‘INFO’ as an alternative to the integer constants such as INFO. Note, however, that levels are internally stored as integers, and methods such as e.g. getEffectiveLevel() and isEnabledFor() will return/expect to be passed integers.  
  
isEnabledFor(level)  
Indicates if a message of severity level would be processed by this logger. This method checks first the module-level level set by logging.disable(level) and then the logger’s effective level as determined by getEffectiveLevel(). 
  
getEffectiveLevel()  
Indicates the effective level for this logger. If a value other than NOTSET has been set using setLevel(), it is returned. Otherwise, the hierarchy is traversed towards the root until a value other than NOTSET is found, and that value is returned. The value returned is an integer, typically one of logging.DEBUG, logging.INFO etc. 
  
getChild(suffix)  
Returns a logger which is a descendant to this logger, as determined by the suffix. Thus, logging.getLogger('abc').getChild('def.ghi') would return the same logger as would be returned by logging.getLogger('abc.def.ghi'). This is a convenience method, useful when the parent logger is named using e.g. __name__ rather than a literal string.  New in version 3.2.  
  
debug(msg, *args, **kwargs)  
Logs a message with level DEBUG on this logger. The msg is the message format string, and the args are the arguments which are merged into msg using the string formatting operator. (Note that this means that you can use keywords in the format string, together with a single dictionary argument.) No % formatting operation is performed on msg when no args are supplied. There are four keyword arguments in kwargs which are inspected: exc_info, stack_info, stacklevel and extra. If exc_info does not evaluate as false, it causes exception information to be added to the logging message. If an exception tuple (in the format returned by sys.exc_info()) or an exception instance is provided, it is used; otherwise, sys.exc_info() is called to get the exception information. The second optional keyword argument is stack_info, which defaults to False. If true, stack information is added to the logging message, including the actual logging call. Note that this is not the same stack information as that displayed through specifying exc_info: The former is stack frames from the bottom of the stack up to the logging call in the current thread, whereas the latter is information about stack frames which have been unwound, following an exception, while searching for exception handlers. You can specify stack_info independently of exc_info, e.g. to just show how you got to a certain point in your code, even when no exceptions were raised. The stack frames are printed following a header line which says: Stack (most recent call last):
 This mimics the Traceback (most recent call last): which is used when displaying exception frames. The third optional keyword argument is stacklevel, which defaults to 1. If greater than 1, the corresponding number of stack frames are skipped when computing the line number and function name set in the LogRecord created for the logging event. This can be used in logging helpers so that the function name, filename and line number recorded are not the information for the helper function/method, but rather its caller. The name of this parameter mirrors the equivalent one in the warnings module. The fourth keyword argument is extra which can be used to pass a dictionary which is used to populate the __dict__ of the LogRecord created for the logging event with user-defined attributes. These custom attributes can then be used as you like. For example, they could be incorporated into logged messages. For example: FORMAT = '%(asctime)-15s %(clientip)s %(user)-8s %(message)s'
logging.basicConfig(format=FORMAT)
d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
logger = logging.getLogger('tcpserver')
logger.warning('Protocol problem: %s', 'connection reset', extra=d)
 would print something like 2006-02-08 22:20:02,165 192.168.0.1 fbloggs  Protocol problem: connection reset
 The keys in the dictionary passed in extra should not clash with the keys used by the logging system. (See the Formatter documentation for more information on which keys are used by the logging system.) If you choose to use these attributes in logged messages, you need to exercise some care. In the above example, for instance, the Formatter has been set up with a format string which expects ‘clientip’ and ‘user’ in the attribute dictionary of the LogRecord. If these are missing, the message will not be logged because a string formatting exception will occur. So in this case, you always need to pass the extra dictionary with these keys. While this might be annoying, this feature is intended for use in specialized circumstances, such as multi-threaded servers where the same code executes in many contexts, and interesting conditions which arise are dependent on this context (such as remote client IP address and authenticated user name, in the above example). In such circumstances, it is likely that specialized Formatters would be used with particular Handlers.  Changed in version 3.2: The stack_info parameter was added.   Changed in version 3.5: The exc_info parameter can now accept exception instances.   Changed in version 3.8: The stacklevel parameter was added.  
  
info(msg, *args, **kwargs)  
Logs a message with level INFO on this logger. The arguments are interpreted as for debug(). 
  
warning(msg, *args, **kwargs)  
Logs a message with level WARNING on this logger. The arguments are interpreted as for debug().  Note There is an obsolete method warn which is functionally identical to warning. As warn is deprecated, please do not use it - use warning instead.  
  
error(msg, *args, **kwargs)  
Logs a message with level ERROR on this logger. The arguments are interpreted as for debug(). 
  
critical(msg, *args, **kwargs)  
Logs a message with level CRITICAL on this logger. The arguments are interpreted as for debug(). 
  
log(level, msg, *args, **kwargs)  
Logs a message with integer level level on this logger. The other arguments are interpreted as for debug(). 
  
exception(msg, *args, **kwargs)  
Logs a message with level ERROR on this logger. The arguments are interpreted as for debug(). Exception info is added to the logging message. This method should only be called from an exception handler. 
  
addFilter(filter)  
Adds the specified filter filter to this logger. 
  
removeFilter(filter)  
Removes the specified filter filter from this logger. 
  
filter(record)  
Apply this logger’s filters to the record and return True if the record is to be processed. The filters are consulted in turn, until one of them returns a false value. If none of them return a false value, the record will be processed (passed to handlers). If one returns a false value, no further processing of the record occurs. 
  
addHandler(hdlr)  
Adds the specified handler hdlr to this logger. 
  
removeHandler(hdlr)  
Removes the specified handler hdlr from this logger. 
  
findCaller(stack_info=False, stacklevel=1)  
Finds the caller’s source filename and line number. Returns the filename, line number, function name and stack information as a 4-element tuple. The stack information is returned as None unless stack_info is True. The stacklevel parameter is passed from code calling the debug() and other APIs. If greater than 1, the excess is used to skip stack frames before determining the values to be returned. This will generally be useful when calling logging APIs from helper/wrapper code, so that the information in the event log refers not to the helper/wrapper code, but to the code that calls it. 
  
handle(record)  
Handles a record by passing it to all handlers associated with this logger and its ancestors (until a false value of propagate is found). This method is used for unpickled records received from a socket, as well as those created locally. Logger-level filtering is applied using filter(). 
  
makeRecord(name, level, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)  
This is a factory method which can be overridden in subclasses to create specialized LogRecord instances. 
  
hasHandlers()  
Checks to see if this logger has any handlers configured. This is done by looking for handlers in this logger and its parents in the logger hierarchy. Returns True if a handler was found, else False. The method stops searching up the hierarchy whenever a logger with the ‘propagate’ attribute set to false is found - that will be the last logger which is checked for the existence of handlers.  New in version 3.2.  
  Changed in version 3.7: Loggers can now be pickled and unpickled.