CLI python2 / mutagen audio tag editor

tag.py

#!/usr/bin/env python2

from argparse import ArgumentParser
from sys import stderr

import mutagen

def get_args():
    parser = ArgumentParser(description='view and edit audio tags')
    parser.add_argument('-t', '--title', type=str, help='set title')
    parser.add_argument('-r', '--artist', type=str, help='set artist')
    parser.add_argument('-l', '--album', type=str, help='set album')
    parser.add_argument('-n', '--tracknumber', type=str,
                        help='set tracknumber')
    parser.add_argument('-d', '--date', type=str, help='set date')
    parser.add_argument('-v', '--view', action='store_true',
                        help='view tags after edits are made')
    parser.add_argument('FILE', type=str, nargs='*',
                        help='files on which to operate')
    return parser.parse_args()

def set_tag(audio, key, value, filename):
    if value:
        try:
            audio[key] = value
        except KeyError:
            stderr.write('failed to set %s for %s\n' % (key, filename))

def run():
    args = get_args()
    tags = {
        'title': args.title,
        'artist': args.artist,
        'album': args.album,
        'tracknumber': args.tracknumber,
        'date': args.date,
    }
    for filename in args.FILE:
        try:
            audio = mutagen.File(filename, easy=True)
        except BaseException as e:
            stderr.write(str(e) + '\n')
            continue
        if audio:
            for key, value in tags.items():
                set_tag(audio, key, value, filename)
            if args.view:
                print(filename + ':')
                print(audio.pprint())
            audio.save()
        else:
            stderr.write('failed to open file: %s\n' % filename)

if __name__ == '__main__':
    run()

in your past revisions, the audio.save() got lost, so changes are never written. Not sure about the .decode(), I thought argparse can handle the encoding.

--- a/tag.py
+++ b/tag.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 
 from argparse import ArgumentParser
 from sys import stderr
@@ -21,7 +21,6 @@ def get_args():
 
 def set_tag(audio, key, value, filename):
     if value:
-        value = value.decode('utf-8', 'replace')
         try:
             audio[key] = value
         except KeyError:
@@ -43,11 +42,13 @@ def run():
             stderr.write(str(e) + '\n')
             continue
         if audio:
-            for key, value in tags.items():
+            for key, value in list(tags.items()):
                 set_tag(audio, key, value, filename)
             if args.view:
                 print(filename + ':')
                 print(audio.pprint())
+            audio.save()
+

Yeah, a string can't be decoded, so that line of code shouldn't be there. Is there a reason for making tags.items() into a list? The object is iterable without doing that.

list() is proposed by the 2to3 conversion util, and according to this answer errs on the safe side for python3 to provide the same snapshotting character of items() in python2.

But as the loop just set_tag()'s and no change occurs on the iterable, there's practical no difference for the code at hand.