is this wrong, feels so wrong

unsync.py

@@ -13,6 +13,10 @@ import mutagen
 import mutaext
 import convert
 
+# BUG: doesn't work with my .m4a files?
+goodexts = ('.mp3', '.m4a', '.flac', '.ogg')
+
+matchtags = ['artist', 'album', 'title']
 updatabletags = [\
     'albumartist', 'composer', 'comment' \
     'tracknumber', 'discnumber', \
@@ -20,99 +24,71 @@ updatabletags = [\
 ]
 updatabletags.extend(mutaext.replaygain_tags)
 updatabletags.extend(mutaext.extra_tags)
-
 alltags = list(updatabletags)
-alltags.extend(['artist', 'album', 'title'])
+alltags.extend(matchtags)
 
-def walkfiles(walker):
-    for root, _, files in walker:
-        for f in files:
-            yield os.path.join(root, f)
-
-def filterext(paths, exts):
-    for p in paths:
-        ext = os.path.splitext(p)[1].lower()
-        if ext in exts:
-            yield p
+lament = lambda *args, **kwargs: print(*args, file=sys.stderr, **kwargs)
+walkfiles = lambda w: (os.path.join(r, f) for r, _, fs in w for f in fs)
+extof = lambda p: os.path.splitext(p)[1].lower()
+filterext = lambda ps, es: (p for p in ps if extof(p) in es)
 
 def shouldsync(md):
     rating = md.get('rating')
     sync = md.get('sync', u'')
     try:
         rating = int(rating[0])
-    except:
+    except (IndexError, ValueError):
         pass
     if sync:
         sync = sync[0].lower()
 
-    if sync == u'no' or sync == u'space':
-        return False
-    if sync == u'yes' or sync == u'share':
-        return True
-    if type(rating) == int and rating >= 3:
-        return True
-    return False
+    return sync == 'yes' or type(rating) == int and rating >= 3 and not sync is 'no' and not sync is 'space'
 
 def fixmetadata(md):
-    md['artist'] = md.get('artist', "Unknown Artist")
-    md['album'] = md.get('album', "Unknown Album")
+    md['artist'] = md.get('artist', u"Unknown Artist")
+    md['album'] = md.get('album', u"Unknown Album")
     if 'title' not in md:
         fn = os.path.basename(md.path)
         fn = os.path.splitext(fn)[0]
         # TODO: attempt to infer trackNum/discNum from fn
-        md['title'] = fn
+        md['title'] = unicode(fn)
 
 def findmatching(haystack, needle):
-    # TODO: don't match mismatched lengths (Xing?)
-    artist = needle.get('artist')
-    album = needle.get('album')
-    title = needle.get('title')
-    match = None
-    for hay in haystack:
-        if artist == hay.get('artist') \
-          and album == hay.get('album') \
-          and title == hay.get('title'):
-            match = hay
-            if match.seen:
-                # TODO: check other tags and filename and such?
-                print("Warning: duplicate match found:", file=sys.stderr)
-                print("{0} by {1} from {2}".format(artist,album,title), file=sys.stderr)
-            else:
-                match.seen = True
-                break
-    return match
+    matchme = [needle[t] for t in matchtags]
+    ismatch = lambda hay: [hay[t] for t in matchtags] == matchme
+    for match in (hay for hay in haystack if ismatch(hay)):
+        if match.seen:
+            # TODO: check other tags and filename and such?
+            lament("Warning: duplicate match found:")
+            lament(u"%(title)s by %(artist)s from %(album)s" % locals())
+        match.seen = True
+        return match
 
 def updatemetadata(mdold, mdnew):
     modified = False
     for tag in updatabletags:
+        # checking for length b/c sometimes (ID3 genre) exists but empty
         if tag in mdnew and len(mdnew[tag]):
             if not tag in mdold or mdnew[tag][0] != mdold[tag][0]:
                 mdold[tag] = mdnew[tag]
                 modified = True
         elif tag in mdold:
             del mdold[tag]
-            print('del', tag)
             modified = True
     return modified
 
 def makefilename(md):
-    fn = ""
     title = md['title'][0]
     artist = md['artist'][0]
     album = md['album'][0]
-    fn = u"{1} - {2} - {0}".format(title,artist,album)
-    fn += ".ogg"
-    return fn
+    return u"%(artist)s - %(album)s - %(title)s.ogg" % locals()
 
 def run(args):
     if not len(args) in (2, 3):
-        print("I need a path or two!", file=sys.stderr)
+        lament("I need a path or two!")
         return 1
-
     inonly = len(args) == 2
 
-    # BUG: doesn't work with my .m4a files?
-    goodexts = ('.mp3', '.m4a', '.flac', '.ogg')
     tosync = []
     indir = args[1]
     paths = lambda dir: filterext(walkfiles(os.walk(dir)), goodexts)
@@ -132,19 +108,18 @@ def run(args):
     if inonly:
         return 0
 
-    print("Matching...", file=sys.stderr)
+    lament("Matching...")
 
     outdir = args[2]
     for p in paths(outdir):
         md = mutagen.File(p, easy=True)
         match = findmatching(tosync, md)
-        if match:
-            if updatemetadata(md, match):
-                print("UPD", p)
-                md.save()
-        else:
+        if not match:
             print("DEL", p)
             os.remove(p)
+        elif updatemetadata(md, match):
+            print("UPD", p)
+            md.save()
 
     for md in tosync:
         if md.seen: