Allow opts.cachedir == None to disable cache

youtube_dl/YoutubeDL.py

@@ -82,7 +82,7 @@ class YoutubeDL(object):
     daterange:         A DateRange object, download only if the upload_date is in the range.
     skip_download:     Skip the actual download of the video file
     cachedir:          Location of the cache files in the filesystem.
-                       "NONE" to disable filesystem cache.
+                       None to disable filesystem cache.
     
     The following parameters are not used by YoutubeDL itself, they are used by
     the FileDownloader:

youtube_dl/__init__.py

@@ -618,7 +618,7 @@ def _real_main(argv=None):
         'min_filesize': opts.min_filesize,
         'max_filesize': opts.max_filesize,
         'daterange': date,
-        'cachedir': opts.cachedir,
+        'cachedir': opts.cachedir if opts.cachedir != 'NONE' else None,
         'youtube_print_sig_code': opts.youtube_print_sig_code,
         })
 

youtube_dl/extractor/youtube.py

@@ -438,7 +438,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor, SubtitlesInfoExtractor):
         cache_dir = self._downloader.params.get('cachedir',
                                                 u'~/.youtube-dl/cache')
 
-        cache_enabled = cache_dir != u'NONE'
+        cache_enabled = cache_dir is not None
         if cache_enabled:
             cache_fn = os.path.join(os.path.expanduser(cache_dir),
                                     u'youtube-sigfuncs',