refactor: replace string concatenations with f-strings

youtube/yt_data_extract/watch_extraction.py

@@ -650,9 +650,9 @@ def _extract_playability_error(info, player_response, error_prefix=''):
     )
 
     if playability_status not in (None, 'OK'):
-        info['playability_error'] = error_prefix + playability_reason
+        info['playability_error'] = f'{error_prefix}{playability_reason}'
     elif not info['playability_error']: # do not override
-        info['playability_error'] = error_prefix + 'Unknown playability error'
+        info['playability_error'] = f'{error_prefix}Unknown playability error'
 
 SUBTITLE_FORMATS = ('srv1', 'srv2', 'srv3', 'ttml', 'vtt')
 def extract_watch_info(polymer_json):
@@ -726,7 +726,7 @@ def extract_watch_info(polymer_json):
         # Store the full URL from the player response (includes valid tokens)
         if base_url:
             normalized = normalize_url(base_url) if base_url.startswith('/') or not base_url.startswith('http') else base_url
-            info['_caption_track_urls'][lang_code + ('_asr' if caption_track.get('kind') == 'asr' else '')] = normalized
+            info['_caption_track_urls'][f'{lang_code}_{"asr" if caption_track.get("kind") == "asr" else ""}'] = normalized
         lang_name = deep_get(urllib.parse.parse_qs(urllib.parse.urlparse(base_url).query), 'name', 0)
         if lang_name:
             info['_manual_caption_language_names'][lang_code] = lang_name
@@ -806,7 +806,7 @@ def extract_watch_info(polymer_json):
     info['allowed_countries'] = mf.get('availableCountries', [])
 
     # other stuff
-    info['author_url'] = 'https://www.youtube.com/channel/' + info['author_id'] if info['author_id'] else None
+    info['author_url'] = f'https://www.youtube.com/channel/{info["author_id"]}' if info['author_id'] else None
     info['storyboard_spec_url'] = deep_get(player_response, 'storyboards', 'playerStoryboardSpecRenderer', 'spec')
 
     return info
@@ -912,12 +912,12 @@ def get_caption_url(info, language, format, automatic=False, translation_languag
     url = info['_captions_base_url']
     if not url:
         return None
-    url += '&lang=' + language
-    url += '&fmt=' + format
+    url += f'&lang={language}'
+    url += f'&fmt={format}'
     if automatic:
         url += '&kind=asr'
     elif language in info['_manual_caption_language_names']:
-        url += '&name=' + urllib.parse.quote(info['_manual_caption_language_names'][language], safe='')
+        url += f'&name={urllib.parse.quote(info["_manual_caption_language_names"][language], safe="")}'
 
     if translation_language:
         url += '&tlang=' + translation_language
@@ -964,7 +964,7 @@ def extract_decryption_function(info, base_js):
         return 'Could not find var_name'
 
     var_name = var_with_operation_match.group(1)
-    var_body_match = re.search(r'var ' + re.escape(var_name) + r'=\{(.*?)\};', base_js, flags=re.DOTALL)
+    var_body_match = re.search(rf'var {re.escape(var_name)}=\{{(.*?)\}};', base_js, flags=re.DOTALL)
     if var_body_match is None:
         return 'Could not find var_body'
 
@@ -988,7 +988,7 @@ def extract_decryption_function(info, base_js):
         elif op_body.startswith('var c=a[0]'):
             operation_definitions[op_name] = 2
         else:
-            return 'Unknown op_body: ' + op_body
+            return f'Unknown op_body: {op_body}'
 
     decryption_function = []
     for op_with_arg in function_body:
@@ -997,7 +997,7 @@ def extract_decryption_function(info, base_js):
             return 'Could not parse operation with arg'
         op_name = match.group(2).strip('[].')
         if op_name not in operation_definitions:
-            return 'Unknown op_name: ' + str(op_name)
+            return f'Unknown op_name: {op_name}'
         op_argument = match.group(3)
         decryption_function.append([operation_definitions[op_name], int(op_argument)])
 
@@ -1028,5 +1028,5 @@ def decrypt_signatures(info):
                 _operation_2(a, argument)
 
         signature = ''.join(a)
-        format['url'] += '&' + format['sp'] + '=' + signature
+        format['url'] += f'&{format["sp"]}={signature}'
     return False