refactored based on wiaterb's suggestion

pytube/contrib/playlist.py

@@ -66,7 +66,7 @@ class Playlist(object):
             complete_url = base_url + video_id
             self.video_urls.append(complete_url)
 
-    def _path_num_prefix_generator(self, reverse_numbering=False):
+    def _path_num_prefix_generator(self, reverse=False):
         """
         This generator function generates number prefixes, for the items
         in the playlist.
@@ -75,25 +75,15 @@ class Playlist(object):
         So if you have a playlist of 100 videos it will number them like:
         001, 002, 003 ect, up to 100.
         It also adds a space after the number.
-        :return: prefix: string
+        :return: prefix string generator : generator
         """
         digits = len(str(len(self.video_urls)))
-        reverse = reverse_numbering
         if reverse:
-            i = len(self.video_urls)
+            start, stop, step = (len(self.video_urls), 0, -1)
         else:
-            i = 1
-        while True:
-            prefix = str(i)
-            if len(prefix) < digits:
-                for _ in range(digits - len(prefix)):
-                    prefix = "0" + prefix
-            prefix += " "
-            if reverse:
-                i -= 1
-            else:
-                i += 1
-            yield prefix
+            start, stop, step = (1, len(self.video_urls) + 1, 1)
+        return (str(i).zfill(digits) for i in range(start, stop, step))
+
 
     def download_all(self, download_path=None, prefix_number=True,
                      reverse_numbering=False):

tests/test_playlist.py

@@ -16,17 +16,6 @@ def test_construct():
     assert ob.construct_playlist_url() == expected
 
 
-def test_link_parse():
-    ob = Playlist(short_test_pl)
-
-    expected = [
-        '/watch?v=m5q2GCsteQs',
-        '/watch?v=5YK63cXyJ2Q',
-        '/watch?v=Rzt4rUPFYD4',
-    ]
-    assert ob.parse_links() == expected
-
-
 def test_populate():
     ob = Playlist(short_test_pl)
     expected = [
@@ -39,6 +28,17 @@ def test_populate():
     assert ob.video_urls == expected
 
 
+def test_link_parse():
+    ob = Playlist(short_test_pl)
+
+    expected = [
+        '/watch?v=m5q2GCsteQs',
+        '/watch?v=5YK63cXyJ2Q',
+        '/watch?v=Rzt4rUPFYD4',
+    ]
+    assert ob.parse_links() == expected
+
+
 def test_download():
     ob = Playlist(short_test_pl)
     ob.download_all()
@@ -50,19 +50,19 @@ def test_download():
 def test_numbering():
     ob = Playlist(short_test_pl)
     ob.populate_video_urls()
-    gen = ob._path_num_prefix_generator(reverse_numbering=False)
+    gen = ob._path_num_prefix_generator(reverse=False)
     assert "1" in next(gen)
     assert "2" in next(gen)
 
     ob = Playlist(short_test_pl)
     ob.populate_video_urls()
-    gen = ob._path_num_prefix_generator(reverse_numbering=True)
+    gen = ob._path_num_prefix_generator(reverse=True)
     assert str(len(ob.video_urls)) in next(gen)
     assert str(len(ob.video_urls) - 1) in next(gen)
 
     ob = Playlist(long_test_pl)
     ob.populate_video_urls()
-    gen = ob._path_num_prefix_generator(reverse_numbering=False)
+    gen = ob._path_num_prefix_generator(reverse=False)
     nxt = next(gen)
     assert len(nxt) > 1
     assert "1" in nxt
@@ -72,6 +72,6 @@ def test_numbering():
 
     ob = Playlist(long_test_pl)
     ob.populate_video_urls()
-    gen = ob._path_num_prefix_generator(reverse_numbering=True)
+    gen = ob._path_num_prefix_generator(reverse=True)
     assert str(len(ob.video_urls)) in next(gen)
     assert str(len(ob.video_urls) - 1) in next(gen)