Use PluginFunctions and PluginPriority to reduce code redundancy.

weight was renamed priority
Execution loops were replaced by PluginFunctions.run() call

picard/metadata.py

@@ -28,7 +28,7 @@
 from os import fdopen, unlink
 from PyQt4.QtCore import QObject
 from picard import config, log
-from picard.plugin import ExtensionPoint
+from picard.plugin import PluginFunctions, PluginPriority
 from picard.similarity import similarity2
 from picard.util import (
     encode_filename,
@@ -439,34 +439,23 @@ def strip_whitespace(self):
         self.apply_func(lambda s: s.strip())
 
 
-from collections import defaultdict
+_album_metadata_processors = PluginFunctions()
+_track_metadata_processors = PluginFunctions()
 
-_album_metadata_processors = defaultdict(ExtensionPoint)
-_track_metadata_processors = defaultdict(ExtensionPoint)
 
-
-def register_album_metadata_processor(function, weight=100):
+def register_album_metadata_processor(function, priority=PluginPriority.NORMAL):
     """Registers new album-level metadata processor."""
-    _album_metadata_processors[weight].register(function.__module__, function)
+    _album_metadata_processors.register(function.__module__, function, priority)
 
 
-def register_track_metadata_processor(function, weight=100):
+def register_track_metadata_processor(function, priority=PluginPriority.NORMAL):
     """Registers new track-level metadata processor."""
-    _track_metadata_processors[weight].register(function.__module__, function)
+    _track_metadata_processors.register(function.__module__, function, priority)
 
 
 def run_album_metadata_processors(tagger, metadata, release):
-    for weight, processors in sorted(_album_metadata_processors.iteritems(),
-                                    key=lambda (k, v): k,
-                                    reverse=True):
-        for processor in processors:
-            processor(tagger, metadata, release)
+    _album_metadata_processors.run(tagger, metadata, release)
 
 
 def run_track_metadata_processors(tagger, metadata, release, track):
-    for weight, processors in sorted(_track_metadata_processors.iteritems(),
-                                    key=lambda (k, v): k,
-                                    reverse=True):
-        for processor in processors:
-            processor(tagger, metadata, track, release)
-
+    _track_metadata_processors.run(tagger, metadata, track, release)