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authorVinay Sajip <vinay_sajip@yahoo.co.uk>2010-12-13 18:43:57 (GMT)
committerVinay Sajip <vinay_sajip@yahoo.co.uk>2010-12-13 18:43:57 (GMT)
commit7292b884bd53c23defc3f52149baed82096b7ff0 (patch)
tree68e65d1613552887098db1ef258a1b174356e97f /Doc/library/logging.rst
parent771d33e1134111a041df78acf7761a9f015d4ea5 (diff)
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Logging documentation update.
Diffstat (limited to 'Doc/library/logging.rst')
-rw-r--r--Doc/library/logging.rst238
1 files changed, 128 insertions, 110 deletions
diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst
index b59315e..032984b 100644
--- a/Doc/library/logging.rst
+++ b/Doc/library/logging.rst
@@ -270,10 +270,11 @@ which would print::
Notice that the 'root' which appeared in earlier examples has disappeared. For
a full set of things that can appear in format strings, you can refer to the
-documentation for :ref:`formatter-objects`, but for simple usage, you just need
-the *levelname* (severity), *message* (event description, including variable
-data) and perhaps to display when the event occurred. This is described in the
-next section.
+documentation for :ref:`logrecord-attributes`, but for simple usage, you just
+need the *levelname* (severity), *message* (event description, including
+variable data) and perhaps to display when the event occurred. This is
+described in the next section.
+
Displaying the date/time in messages
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -524,10 +525,10 @@ or '$'. If one of these is not specified, then '%' will be used.
If the ``style`` is '%', the message format string uses
``%(<dictionary key>)s`` styled string substitution; the possible keys are
-documented in :ref:`formatter-objects`. If the style is '{', the message format
-string is assumed to be compatible with :meth:`str.format` (using keyword
-arguments), while if the style is '$' then the message format string should
-conform to what is expected by :meth:`string.Template.substitute`.
+documented in :ref:`logrecord-attributes`. If the style is '{', the message
+format string is assumed to be compatible with :meth:`str.format` (using
+keyword arguments), while if the style is '$' then the message format string
+should conform to what is expected by :meth:`string.Template.substitute`.
.. versionchanged:: 3.2
Added the ``style`` parameter.
@@ -3260,7 +3261,9 @@ The :class:`QueueListener` class, located in the :mod:`logging.handlers`
module, supports receiving logging messages from a queue, such as those
implemented in the :mod:`queue` or :mod:`multiprocessing` modules. The
messages are received from a queue in an internal thread and passed, on
-the same thread, to one or more handlers for processing.
+the same thread, to one or more handlers for processing. While
+:class:`QueueListener` is not itself a handler, it is documented here
+because it works hand-in-hand with :class:`QueueHandler`.
Along with the :class:`QueueHandler` class, :class:`QueueListener` can be used
to let handlers do their work on a separate thread from the one which does the
@@ -3384,7 +3387,7 @@ Formatter Objects
.. currentmodule:: logging
-:class:`Formatter`\ s have the following attributes and methods. They are
+:class:`Formatter` objects have the following attributes and methods. They are
responsible for converting a :class:`LogRecord` to (usually) a string which can
be interpreted by either a human or an external system. The base
:class:`Formatter` allows a formatting string to be specified. If none is
@@ -3397,61 +3400,8 @@ into a :class:`LogRecord`'s *message* attribute. This format string contains
standard Python %-style mapping keys. See section :ref:`old-string-formatting`
for more information on string formatting.
-Currently, the useful mapping keys in a :class:`LogRecord` are:
-
-+-------------------------+-----------------------------------------------+
-| Format | Description |
-+=========================+===============================================+
-| ``%(name)s`` | Name of the logger (logging channel). |
-+-------------------------+-----------------------------------------------+
-| ``%(levelno)s`` | Numeric logging level for the message |
-| | (:const:`DEBUG`, :const:`INFO`, |
-| | :const:`WARNING`, :const:`ERROR`, |
-| | :const:`CRITICAL`). |
-+-------------------------+-----------------------------------------------+
-| ``%(levelname)s`` | Text logging level for the message |
-| | (``'DEBUG'``, ``'INFO'``, ``'WARNING'``, |
-| | ``'ERROR'``, ``'CRITICAL'``). |
-+-------------------------+-----------------------------------------------+
-| ``%(pathname)s`` | Full pathname of the source file where the |
-| | logging call was issued (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(filename)s`` | Filename portion of pathname. |
-+-------------------------+-----------------------------------------------+
-| ``%(module)s`` | Module (name portion of filename). |
-+-------------------------+-----------------------------------------------+
-| ``%(funcName)s`` | Name of function containing the logging call. |
-+-------------------------+-----------------------------------------------+
-| ``%(lineno)d`` | Source line number where the logging call was |
-| | issued (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(created)f`` | Time when the :class:`LogRecord` was created |
-| | (as returned by :func:`time.time`). |
-+-------------------------+-----------------------------------------------+
-| ``%(relativeCreated)d`` | Time in milliseconds when the LogRecord was |
-| | created, relative to the time the logging |
-| | module was loaded. |
-+-------------------------+-----------------------------------------------+
-| ``%(asctime)s`` | Human-readable time when the |
-| | :class:`LogRecord` was created. By default |
-| | this is of the form "2003-07-08 16:49:45,896" |
-| | (the numbers after the comma are millisecond |
-| | portion of the time). |
-+-------------------------+-----------------------------------------------+
-| ``%(msecs)d`` | Millisecond portion of the time when the |
-| | :class:`LogRecord` was created. |
-+-------------------------+-----------------------------------------------+
-| ``%(thread)d`` | Thread ID (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(threadName)s`` | Thread name (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(process)d`` | Process ID (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(processName)s`` | Process name (if available). |
-+-------------------------+-----------------------------------------------+
-| ``%(message)s`` | The logged message, computed as ``msg % |
-| | args``. |
-+-------------------------+-----------------------------------------------+
+The useful mapping keys in a :class:`LogRecord` are given in the section on
+:ref:`logrecord-attributes`.
.. class:: Formatter(fmt=None, datefmt=None)
@@ -3577,7 +3527,7 @@ every time something is logged, and can be created manually via
wire).
-.. class:: LogRecord(name, levelno, pathname, lineno, msg, args, exc_info, func=None, sinfo=None)
+.. class:: LogRecord(name, level, pathname, lineno, msg, args, exc_info, func=None, sinfo=None)
Contains all the information pertinent to the event being logged.
@@ -3585,50 +3535,23 @@ wire).
are combined using ``msg % args`` to create the :attr:`message` field of the
record.
- .. attribute:: args
-
- Tuple of arguments to be used in formatting :attr:`msg`.
-
- .. attribute:: exc_info
-
- Exception tuple (à la :func:`sys.exc_info`) or ``None`` if no exception
- information is available.
-
- .. attribute:: func
-
- Name of the function of origin (i.e. in which the logging call was made).
-
- .. attribute:: lineno
-
- Line number in the source file of origin.
-
- .. attribute:: levelno
-
- Numeric logging level.
-
- .. attribute:: message
-
- Bound to the result of :meth:`getMessage` when
- :meth:`Formatter.format(record)<Formatter.format>` is invoked.
-
- .. attribute:: msg
-
- User-supplied :ref:`format string<string-formatting>` or arbitrary object
- (see :ref:`arbitrary-object-messages`) used in :meth:`getMessage`.
-
- .. attribute:: name
-
- Name of the logger that emitted the record.
-
- .. attribute:: pathname
-
- Absolute pathname of the source file of origin.
-
- .. attribute:: stack_info
-
- Stack frame information (where available) from the bottom of the stack
- in the current thread, up to and including the stack frame of the
- logging call which resulted in the creation of this record.
+ :param name: The name of the logger used to log the event represented by
+ this LogRecord.
+ :param level: The numeric level of the logging event (one of DEBUG, INFO etc.)
+ :param pathname: The full pathname of the source file where the logging call
+ was made.
+ :param lineno: The line number in the source file where the logging call was
+ made.
+ :param msg: The event description message, possibly a format string with
+ placeholders for variable data.
+ :param args: Variable data to merge into the *msg* argument to obtain the
+ event description.
+ :param exc_info: An exception tuple with the current exception information,
+ or *None* if no exception information is available.
+ :param func: The name of the function or method from which the logging call
+ was invoked.
+ :param sinfo: A text string representing stack information from the base of
+ the stack in the current thread, up to the logging call.
.. method:: getMessage()
@@ -3663,6 +3586,101 @@ wire).
surprises.
+.. _logrecord-attributes:
+
+``LogRecord`` attributes
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The LogRecord has a number of attributes, most of which are derived from the
+parameters to the constructor. (Note that the names do not always correspond
+exactly between the LogRecord constructor parameters and the LogRecord
+attributes.) These attributes can be used to merge data from the record into
+the format string. The following table lists (in alphabetical order) the
+attribute names, their meanings and the corresponding placeholder in a %-style
+format string.
+
+If you are using {}-formatting (:func:`str.format`), you can use
+``{{attrname}}`` as the placeholder in the format string. If you are using
+$-formatting (:class:`string.Template`), use the form ``${attrname}``. In
+both cases, of course, replace ``attrname`` with the actual attribute name
+you want to use.
+
+In the case of {}-formatting, you can specify formatting flags by placing them
+after the attribute name, separated from it with a colon.
+
++----------------+-------------------------+-----------------------------------------------+
+| Attribute name | Format | Description |
++================+=========================+===============================================+
+| args | You shouldn't need to | The tuple of arguments merged into ``msg`` to |
+| | format this yourself. | produce ``message``. |
++----------------+-------------------------+-----------------------------------------------+
+| asctime | ``%(asctime)s`` | Human-readable time when the |
+| | | :class:`LogRecord` was created. By default |
+| | | this is of the form "2003-07-08 16:49:45,896" |
+| | | (the numbers after the comma are millisecond |
+| | | portion of the time). |
++----------------+-------------------------+-----------------------------------------------+
+| created | ``%(created)f`` | Time when the :class:`LogRecord` was created |
+| | | (as returned by :func:`time.time`). |
++----------------+-------------------------+-----------------------------------------------+
+| exc_info | You shouldn't need to | Exception tuple (à la ``sys.exc_info``) or, |
+| | format this yourself. | if no exception has occurred, *None*. |
++----------------+-------------------------+-----------------------------------------------+
+| filename | ``%(filename)s`` | Filename portion of ``pathname``. |
++----------------+-------------------------+-----------------------------------------------+
+| funcName | ``%(funcName)s`` | Name of function containing the logging call. |
++----------------+-------------------------+-----------------------------------------------+
+| levelname | ``%(levelname)s`` | Text logging level for the message |
+| | | (``'DEBUG'``, ``'INFO'``, ``'WARNING'``, |
+| | | ``'ERROR'``, ``'CRITICAL'``). |
++----------------+-------------------------+-----------------------------------------------+
+| levelno | ``%(levelno)s`` | Numeric logging level for the message |
+| | | (:const:`DEBUG`, :const:`INFO`, |
+| | | :const:`WARNING`, :const:`ERROR`, |
+| | | :const:`CRITICAL`). |
++----------------+-------------------------+-----------------------------------------------+
+| lineno | ``%(lineno)d`` | Source line number where the logging call was |
+| | | issued (if available). |
++----------------+-------------------------+-----------------------------------------------+
+| module | ``%(module)s`` | Module (name portion of ``filename``). |
++----------------+-------------------------+-----------------------------------------------+
+| msecs | ``%(msecs)d`` | Millisecond portion of the time when the |
+| | | :class:`LogRecord` was created. |
++----------------+-------------------------+-----------------------------------------------+
+| message | ``%(message)s`` | The logged message, computed as ``msg % |
+| | | args``. This is set when |
+| | | :meth:`Formatter.format` is invoked. |
++----------------+-------------------------+-----------------------------------------------+
+| msg | You shouldn't need to | The format string passed in the original |
+| | format this yourself. | logging call. Merged with ``args`` to |
+| | | produce ``message``, or an arbitrary object |
+| | | (see :ref:`arbitrary-object-messages`). |
++----------------+-------------------------+-----------------------------------------------+
+| name | ``%(name)s`` | Name of the logger used to log the call. |
++----------------+-------------------------+-----------------------------------------------+
+| pathname | ``%(pathname)s`` | Full pathname of the source file where the |
+| | | logging call was issued (if available). |
++----------------+-------------------------+-----------------------------------------------+
+| process | ``%(process)d`` | Process ID (if available). |
++----------------+-------------------------+-----------------------------------------------+
+| processName | ``%(processName)s`` | Process name (if available). |
++----------------+-------------------------+-----------------------------------------------+
+| relativeCreated| ``%(relativeCreated)d`` | Time in milliseconds when the LogRecord was |
+| | | created, relative to the time the logging |
+| | | module was loaded. |
++----------------+-------------------------+-----------------------------------------------+
+| stack_info | You shouldn't need to | Stack frame information (where available) |
+| | format this yourself. | from the bottom of the stack in the current |
+| | | thread, up to and including the stack frame |
+| | | of the logging call which resulted in the |
+| | | creation of this record. |
++----------------+-------------------------+-----------------------------------------------+
+| thread | ``%(thread)d`` | Thread ID (if available). |
++----------------+-------------------------+-----------------------------------------------+
+| threadName | ``%(threadName)s`` | Thread name (if available). |
++----------------+-------------------------+-----------------------------------------------+
+
+
.. _logger-adapter:
LoggerAdapter Objects