ext: Make get_{cache,config,data}_dir() class methods

Fixes #1275

docs/changelog.rst

@@ -28,6 +28,12 @@ Bug fix release.
 - Core: Fix error in :meth:`~mopidy.core.TracklistController.get_eot_tlid`
   docstring. (Fixes: :issue:`1269`)
 
+- Extension support: Make :meth:`~mopidy.ext.Extension.get_cache_dir`,
+  :meth:`~mopidy.ext.Extension.get_config_dir`, and
+  :meth:`~mopidy.ext.Extension.get_data_dir` class methods, so they can be used
+  without creating an instance of the :class:`~mopidy.ext.Extension` class.
+  (Fixes: :issue:`1275`)
+
 - Local: Deprecate :confval:`local/data_dir` and respect
   :confval:`core/data_dir` instead. This does not change the defaults for
   desktop users, only system services installed from packages that properly set

mopidy/ext.py

@@ -60,7 +60,8 @@ class Extension(object):
         schema['enabled'] = config_lib.Boolean()
         return schema
 
-    def get_cache_dir(self, config):
+    @classmethod
+    def get_cache_dir(cls, config):
         """Get or create cache directory for the extension.
 
         Use this directory to cache data that can safely be thrown away.
@@ -68,25 +69,27 @@ class Extension(object):
         :param config: the Mopidy config object
         :return: string
         """
-        assert self.ext_name is not None
+        assert cls.ext_name is not None
         cache_dir_path = bytes(os.path.join(config['core']['cache_dir'],
-                                            self.ext_name))
+                                            cls.ext_name))
         path.get_or_create_dir(cache_dir_path)
         return cache_dir_path
 
-    def get_config_dir(self, config):
+    @classmethod
+    def get_config_dir(cls, config):
         """Get or create configuration directory for the extension.
 
         :param config: the Mopidy config object
         :return: string
         """
-        assert self.ext_name is not None
+        assert cls.ext_name is not None
         config_dir_path = bytes(os.path.join(config['core']['config_dir'],
-                                             self.ext_name))
+                                             cls.ext_name))
         path.get_or_create_dir(config_dir_path)
         return config_dir_path
 
-    def get_data_dir(self, config):
+    @classmethod
+    def get_data_dir(cls, config):
         """Get or create data directory for the extension.
 
         Use this directory to store data that should be persistent.
@@ -94,9 +97,9 @@ class Extension(object):
         :param config: the Mopidy config object
         :returns: string
         """
-        assert self.ext_name is not None
+        assert cls.ext_name is not None
         data_dir_path = bytes(os.path.join(config['core']['data_dir'],
-                                           self.ext_name))
+                                           cls.ext_name))
         path.get_or_create_dir(data_dir_path)
         return data_dir_path
 

mopidy/local/json.py

@@ -12,7 +12,7 @@ import tempfile
 import mopidy
 from mopidy import compat, local, models
 from mopidy.internal import encoding, timer
-from mopidy.local import Extension, search, storage, translator
+from mopidy.local import search, storage, translator
 
 logger = logging.getLogger(__name__)
 
@@ -116,7 +116,7 @@ class JsonLibrary(local.Library):
         self._browse_cache = None
         self._media_dir = config['local']['media_dir']
         self._json_file = os.path.join(
-            Extension().get_data_dir(config), b'library.json.gz')
+            local.Extension.get_data_dir(config), b'library.json.gz')
 
         storage.check_dirs_and_files(config)
 

mopidy/m3u/actor.py

@@ -30,7 +30,7 @@ class M3UBackend(pykka.ThreadingActor, backend.Backend):
                     'Could not create M3U playlists dir: %s',
                     encoding.locale_decode(error))
         else:
-            self._playlists_dir = m3u.Extension().get_data_dir(config)
+            self._playlists_dir = m3u.Extension.get_data_dir(config)
 
         self.playlists = M3UPlaylistsProvider(backend=self)
         self.library = M3ULibraryProvider(backend=self)

tests/test_ext.py

@@ -58,17 +58,17 @@ class TestExtension(object):
     def test_get_cache_dir_raises_assertion_error(self, extension):
         config = {'core': {'cache_dir': '/tmp'}}
         with pytest.raises(AssertionError):  # ext_name not set
-            extension.get_cache_dir(config)
+            ext.Extension.get_cache_dir(config)
 
     def test_get_config_dir_raises_assertion_error(self, extension):
         config = {'core': {'config_dir': '/tmp'}}
         with pytest.raises(AssertionError):  # ext_name not set
-            extension.get_config_dir(config)
+            ext.Extension.get_config_dir(config)
 
     def test_get_data_dir_raises_assertion_error(self, extension):
         config = {'core': {'data_dir': '/tmp'}}
         with pytest.raises(AssertionError):  # ext_name not set
-            extension.get_data_dir(config)
+            ext.Extension.get_data_dir(config)
 
 
 class TestLoadExtensions(object):