Issue #9827: clarified LogRecord documentation.

Doc/library/logging.rst

@@ -527,6 +527,7 @@ libraries, then the logger name specified can be "orgname.foo" rather than
 just "foo".
 
 .. versionadded:: 3.1
+
    The :class:`NullHandler` class was not present in previous versions, but is
    now included, so that it need not be defined in library code.
 
@@ -736,7 +737,7 @@ functions.
       d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
       logging.warning("Protocol problem: %s", "connection reset", extra=d)
 
-   would print something like ::
+   would print something like::
 
       2006-02-08 22:20:02,165 192.168.0.1 fbloggs  Protocol problem: connection reset
 
@@ -903,6 +904,7 @@ functions.
       and 2.2.x, which do not include the :mod:`logging` package in the standard
       library.
 
+.. _logger:
 
 Logger Objects
 --------------
@@ -1788,6 +1790,8 @@ these affect you, you can use an alternative serialization scheme by overriding
 the :meth:`makePickle` method and implementing your alternative there, as
 well as adapting the above script to use your alternative serialization.
 
+.. _arbitrary-object-messages:
+
 Using arbitrary objects as messages
 -----------------------------------
 
@@ -2705,7 +2709,6 @@ Currently, the useful mapping keys in a :class:`LogRecord` are:
    specified, ``'%(message)s'`` is used.  If no *datefmt* is specified, the
    ISO8601 date format is used.
 
-
    .. method:: format(record)
 
       The record's attribute dictionary is used as the operand to a string
@@ -2781,32 +2784,70 @@ been applied to those descendant loggers.
 LogRecord Objects
 -----------------
 
-:class:`LogRecord` instances are created every time something is logged. They
-contain all the information pertinent to the event being logged. The main
-information passed in is in msg and args, which are combined using msg % args to
-create the message field of the record. The record also includes information
-such as when the record was created, the source line where the logging call was
-made, and any exception information to be logged.
+:class:`LogRecord` instances are created automatically by the :class:`Logger`
+every time something is logged, and can be created manually via
+:func:`makeLogRecord` (for example, from a pickled event received over the
+wire).
 
 
 .. class:: LogRecord(name, lvl, pathname, lineno, msg, args, exc_info, func=None)
 
-   Returns an instance of :class:`LogRecord` initialized with interesting
-   information. The *name* is the logger name; *lvl* is the numeric level;
-   *pathname* is the absolute pathname of the source file in which the logging
-   call was made; *lineno* is the line number in that file where the logging
-   call is found; *msg* is the user-supplied message (a format string); *args*
-   is the tuple which, together with *msg*, makes up the user message; and
-   *exc_info* is the exception tuple obtained by calling :func:`sys.exc_info`
-   (or :const:`None`, if no exception information is available). The *func* is
-   the name of the function from which the logging call was made. If not
-   specified, it defaults to ``None``.
+   Contains all the information pertinent to the event being logged.
+
+   The primary information is passed in :attr:`msg` and :attr:`args`, which
+   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 `sys.exc_info`) or `None` if no exception
+      information is availble.
+
+   .. 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:: lvl
+
+      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.
 
    .. method:: getMessage()
 
       Returns the message for this :class:`LogRecord` instance after merging any
-      user-supplied arguments with the message.
+      user-supplied arguments with the message. If the user-supplied message
+      argument to the logging call is not a string, :func:`str` is called on it to
+      convert it to a string. This allows use of user-defined classes as
+      messages, whose ``__str__`` method can return the actual format string to
+      be used.
+
+   .. versionchanged:: 2.5
+      *func* was added.
 
 .. _logger-adapter: