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Diffstat (limited to 'Doc/library/logging.handlers.rst')
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diff --git a/Doc/library/logging.handlers.rst b/Doc/library/logging.handlers.rst index 3911d4d..183d5f9 100644 --- a/Doc/library/logging.handlers.rst +++ b/Doc/library/logging.handlers.rst @@ -164,6 +164,87 @@ this value. changed. If it has, the existing stream is flushed and closed and the file opened again, before outputting the record to the file. +.. _base-rotating-handler: + +BaseRotatingHandler +^^^^^^^^^^^^^^^^^^^ + +The :class:`BaseRotatingHandler` class, located in the :mod:`logging.handlers` +module, is the base class for the rotating file handlers, +:class:`RotatingFileHandler` and :class:`TimedRotatingFileHandler`. You should +not need to instantiate this class, but it has attributes and methods you may +need to override. + +.. class:: BaseRotatingHandler(filename, mode, encoding=None, delay=False) + + The parameters are as for :class:`FileHandler`. The attributes are: + + .. attribute:: namer + + If this attribute is set to a callable, the :meth:`rotation_filename` + method delegates to this callable. The parameters passed to the callable + are those passed to :meth:`rotation_filename`. + + .. note:: The namer function is called quite a few times during rollover, + so it should be as simple and as fast as possible. It should also + return the same output every time for a given input, otherwise the + rollover behaviour may not work as expected. + + .. versionadded:: 3.3 + + + .. attribute:: BaseRotatingHandler.rotator + + If this attribute is set to a callable, the :meth:`rotate` method + delegates to this callable. The parameters passed to the callable are + those passed to :meth:`rotate`. + + .. versionadded:: 3.3 + + .. method:: BaseRotatingHandler.rotation_filename(default_name) + + Modify the filename of a log file when rotating. + + This is provided so that a custom filename can be provided. + + The default implementation calls the 'namer' attribute of the handler, + if it's callable, passing the default name to it. If the attribute isn't + callable (the default is `None`), the name is returned unchanged. + + :param default_name: The default name for the log file. + + .. versionadded:: 3.3 + + + .. method:: BaseRotatingHandler.rotate(source, dest) + + When rotating, rotate the current log. + + The default implementation calls the 'rotator' attribute of the handler, + if it's callable, passing the source and dest arguments to it. If the + attribute isn't callable (the default is `None`), the source is simply + renamed to the destination. + + :param source: The source filename. This is normally the base + filename, e.g. 'test.log' + :param dest: The destination filename. This is normally + what the source is rotated to, e.g. 'test.log.1'. + + .. versionadded:: 3.3 + +The reason the attributes exist is to save you having to subclass - you can use +the same callables for instances of :class:`RotatingFileHandler` and +:class:`TimedRotatingFileHandler`. If either the namer or rotator callable +raises an exception, this will be handled in the same way as any other +exception during an :meth:`emit` call, i.e. via the :meth:`handleError` method +of the handler. + +If you need to make more significant changes to rotation processing, you can +override the methods. + +For an example, see :ref:`cookbook-rotator-namer`. + + .. _rotating-file-handler: RotatingFileHandler |