move api docs to source code

docs/topics/logging.rst

@@ -196,41 +196,11 @@ to override some of the Scrapy settings regarding logging.
 Custom Log Formats
 -------------------
 
-Custom log format can be set for different actions by extending ``scrapy.logformatter.LogFormatter`` class.
-
-Each method of ``scrapy.logformatter.LogFormatter`` represents an action. All methods inherited from 
-``scrapy.logformatter.LogFormatter`` in your custom log formatting class must return a dictionary listing
-the parameters ``level``, ``msg`` and ``args`` which are going to be used for constructing the log message.
-Listed below is details of what each key represents :
-
-*   ``level`` is the log level for that action, you can use those from the python logging library:
-    :setting:`logging.DEBUG`, :setting:`logging.INFO`, :setting:`logging.WARNING`, :setting:`logging.ERROR`
-    and :setting:`logging.CRITICAL`.
-
-*   ``msg`` should be a string that can contain different formatting placeholders. This string, formatted
-    with the provided ``args``, is going to be the long message for that action.
-
-*   ``args`` should be a tuple or dict with the formatting placeholders for `msg`. The final log message is
-    computed as ``msg % args``.
-
-.. note:: To use custom log formatting class, you must mention it in ``settings.py``, by adding a line 
-   ``LOG_FORMATTER = '<path_to_your_class>’``
+Custom log format can be set for different actions by extending :class:`~scrapy.logformatter.LogFormatter` class
+and making :setting:`LOG_FORMATTER` inside ``settings.py`` point to your new class.
  
-.. class:: scrapy.logformatter.LogFormatter
-
-   The default log formatting class in Scrapy.
-
-   .. method:: crawled (request, response, spider)
-
-      ``crawled`` is called to log message when the crawler finds a webpage.
-
-   .. method:: scraped(item, response, spider)
-
-      ``scraped`` is called to log message when an item scraped by a spider.
-
-   .. method::  dropped(item, exception, response, spider)  
-
-      ``dropped`` is called to log message when an item is dropped while it is passing through the item pipeline. 
+.. autoclass:: scrapy.logformatter.LogFormatter
+   :members:
 
 Advanced customization
 ----------------------

docs/topics/settings.rst

@@ -866,6 +866,15 @@ directives.
 
 .. _Python datetime documentation: https://docs.python.org/2/library/datetime.html#strftime-and-strptime-behavior
 
+.. setting:: LOG_FORMATTER
+
+LOG_FORMATTER
+-------------
+
+Default: ``scrapy.logformatter.LogFormatter``
+
+The class to use for formatting log messages for different actions.
+
 .. setting:: LOG_LEVEL
 
 LOG_LEVEL

scrapy/logformatter.py

@@ -13,25 +13,29 @@ CRAWLEDMSG = u"Crawled (%(status)s) %(request)s%(request_flags)s (referer: %(ref
 class LogFormatter(object):
     """Class for generating log messages for different actions.
 
-    All methods must return a dictionary listing the parameters `level`, `msg`
-    and `args` which are going to be used for constructing the log message when
-    calling logging.log.
+    All methods must return a dictionary listing the parameters ``level``, ``msg``
+    and ``args`` which are going to be used for constructing the log message when
+    calling ``logging.log``.
 
     Dictionary keys for the method outputs:
-        * `level` should be the log level for that action, you can use those
-        from the python logging library: logging.DEBUG, logging.INFO,
-        logging.WARNING, logging.ERROR and logging.CRITICAL.
 
-        * `msg` should be a string that can contain different formatting
-        placeholders. This string, formatted with the provided `args`, is going
-        to be the log message for that action.
+        *   ``level`` is the log level for that action, you can use those from the 
+            `python logging library <https://docs.python.org/3/library/logging.html>`_ :
+            ``logging.DEBUG``, ``logging.INFO``, ``logging.WARNING``, ``logging.ERROR``
+            and ``logging.CRITICAL``.
+
+        *   ``msg`` should be a string that can contain different formatting placeholders. This string, formatted
+            with the provided ``args``, is going to be the long message for that action.
+
+        *   ``args`` should be a tuple or dict with the formatting placeholders for ``msg``. The final log message is
+            computed as ``msg % args``.
 
-        * `args` should be a tuple or dict with the formatting placeholders for
-        `msg`.  The final log message is computed as output['msg'] %
-        output['args'].
     """
 
     def crawled(self, request, response, spider):
+        """
+        ``crawled`` is called to log message when the crawler finds a webpage.
+        """
         request_flags = ' %s' % str(request.flags) if request.flags else ''
         response_flags = ' %s' % str(response.flags) if response.flags else ''
         return {
@@ -40,7 +44,7 @@ class LogFormatter(object):
             'args': {
                 'status': response.status,
                 'request': request,
-                'request_flags' : request_flags,
+                'request_flags': request_flags,
                 'referer': referer_str(request),
                 'response_flags': response_flags,
                 # backward compatibility with Scrapy logformatter below 1.4 version
@@ -49,6 +53,9 @@ class LogFormatter(object):
         }
 
     def scraped(self, item, response, spider):
+        """
+        ``scraped`` is called to log message when an item is scraped by a spider.
+        """
         if isinstance(response, Failure):
             src = response.getErrorMessage()
         else:
@@ -63,6 +70,9 @@ class LogFormatter(object):
         }
 
     def dropped(self, item, exception, response, spider):
+        """
+        ``dropped`` is called to log message when an item is dropped while it is passing through the item pipeline. 
+        """
         return {
             'level': logging.WARNING,
             'msg': DROPPEDMSG,