Add null log handler, since spotify.audiosink.gstreamer have started …

…using logging

docs/changes.rst

@@ -41,6 +41,15 @@ v1.7 (in development)
 
 - Added optional argument ``type`` for :class:`spotify.ArtistBrowser`.
 
+- pyspotify now registers a "null handler" for logging to the ``spotify``
+  logger. This means that any pyspotify code is free to log debug log to any
+  logger matching ``spotify.*``.
+
+  By default the log statements will be swallowed by the null handler. An
+  application developer using pyspotify may add an additional log handler which
+  listens for log messages to the ``spotify`` logger, and thus get debug
+  information from pyspotify.
+
 - Bundled audio sink support:
 
   - A audio sink wrapper for `PortAudio

spotify/__init__.py

@@ -3,6 +3,20 @@
 class SpotifyError(Exception):
     pass
 
+# pylint: disable = W0404
+def _add_null_handler_for_logging():
+    import logging
+    try:
+        NullHandler = logging.NullHandler  # Python 2.7 and upwards
+    except AttributeError:
+        class NullHandler(logging.Handler):
+            def emit(self, record):
+                pass
+    logging.getLogger('spotify').addHandler(NullHandler())
+
+_add_null_handler_for_logging()
+# pylint: enable = W0404
+
 from spotify._spotify import Session
 from spotify._spotify import Track
 from spotify._spotify import Artist
@@ -19,3 +33,5 @@ class SpotifyError(Exception):
 
 from spotify._spotify import api_version
 from spotify._spotify import connect
+
+