Deprecate more frequently used functions from scrapy/log.py

scrapy/log.py

@@ -2,9 +2,46 @@
 This module is kept to provide a helpful warning about its removal.
 """
 
+import logging
 import warnings
+
+from twisted.python.failure import Failure
+
 from scrapy.exceptions import ScrapyDeprecationWarning
+
+logger = logging.getLogger('scrapy')
+
 warnings.warn("Module `scrapy.log` has been deprecated, Scrapy now relies on "
               "the builtin Python library for logging. Read the updated "
               "logging entry in the documentation to learn more.",
               ScrapyDeprecationWarning, stacklevel=2)
+
+
+# Imports kept for backwards-compatibility
+
+DEBUG = logging.DEBUG
+INFO = logging.INFO
+WARNING = logging.WARNING
+ERROR = logging.ERROR
+CRITICAL = logging.CRITICAL
+SILENT = CRITICAL + 1
+
+
+def msg(message, _level=logging.INFO, **kw):
+    warnings.warn('log.msg has been deprecated, create a python logger and '
+                  'log through it instead',
+                  ScrapyDeprecationWarning, stacklevel=2)
+
+    level = kw.pop('level', _level)
+    logger.log(level, message, kw)
+
+
+def err(_stuff=None, _why=None, **kw):
+    warnings.warn('log.err has been deprecated, create a python logger and '
+                  'use its error method instead',
+                  ScrapyDeprecationWarning, stacklevel=2)
+
+    level = kw.pop('level', logging.ERROR)
+    failure = kw.pop('failure', _stuff) or Failure()
+    message = kw.pop('why', _why) or failure.value
+    logger.log(level, message, kw, extra={'failure': failure})