pythongh-84095: Fill documentation gap regarding user-defined objects. (pythonGH-96574)

(cherry picked from commit a9d58fe)

Author: vsajip

Doc/library/logging.config.rst

@@ -524,6 +524,25 @@ valid keyword parameter name, and so will not clash with the names of
 the keyword arguments used in the call.  The ``'()'`` also serves as a
 mnemonic that the corresponding value is a callable.
 
+You can also specify a special key ``'.'`` whose value is a dictionary is a
+mapping of attribute names to values. If found, the specified attributes will
+be set on the user-defined object before it is returned. Thus, with the
+following configuration::
+
+    {
+      '()' : 'my.package.customFormatterFactory',
+      'bar' : 'baz',
+      'spam' : 99.9,
+      'answer' : 42,
+      '.' {
+        'foo': 'bar',
+        'baz': 'bozz'
+      }
+    }
+
+the returned formatter will have attribute ``foo`` set to ``'bar'`` and
+attribute ``baz`` set to ``'bozz'``.
+
 
 .. _logging-config-dict-externalobj:
 
@@ -706,7 +725,7 @@ root logger section is given below.
 
 The ``level`` entry can be one of ``DEBUG, INFO, WARNING, ERROR, CRITICAL`` or
 ``NOTSET``. For the root logger only, ``NOTSET`` means that all messages will be
-logged. Level values are :func:`eval`\ uated in the context of the ``logging``
+logged. Level values are :ref:`evaluated <func-eval>` in the context of the ``logging``
 package's namespace.
 
 The ``handlers`` entry is a comma-separated list of handler names, which must
@@ -753,13 +772,13 @@ handler. If blank, a default formatter (``logging._defaultFormatter``) is used.
 If a name is specified, it must appear in the ``[formatters]`` section and have
 a corresponding section in the configuration file.
 
-The ``args`` entry, when :func:`eval`\ uated in the context of the ``logging``
+The ``args`` entry, when :ref:`evaluated <func-eval>` in the context of the ``logging``
 package's namespace, is the list of arguments to the constructor for the handler
 class. Refer to the constructors for the relevant handlers, or to the examples
 below, to see how typical entries are constructed. If not provided, it defaults
 to ``()``.
 
-The optional ``kwargs`` entry, when :func:`eval`\ uated in the context of the
+The optional ``kwargs`` entry, when :ref:`evaluated <func-eval>` in the context of the
 ``logging`` package's namespace, is the keyword argument dict to the constructor
 for the handler class. If not provided, it defaults to ``{}``.
 
@@ -823,7 +842,7 @@ Sections which specify formatter configuration are typified by the following.
    [formatter_form01]
    format=F1 %(asctime)s %(levelname)s %(message)s
    datefmt=
-   style='%'
+   style=%
    validate=True
    class=logging.Formatter