[pylint] prepare for pylint v2.9.3 / fix some (new) pylint issues

Upgrade from pylint v2.8.3 to 2.9.3 raise some new issues::

  searx/search/checker/__main__.py:37:26: R1732: Consider using 'with' for resource-allocating operations (consider-using-with)
  searx/search/checker/__main__.py:38:26: R1732: Consider using 'with' for resource-allocating operations (consider-using-with)
  searx/search/processors/__init__.py:20:0: R0402: Use 'from searx import engines' instead (consider-using-from-import)
  searx/preferences.py:182:19: C0207: Use data.split('-', maxsplit=1)[0] instead (use-maxsplit-arg)
  searx/preferences.py:506:15: R1733: Unnecessary dictionary index lookup, use 'user_setting' instead (unnecessary-dict-index-lookup)
  searx/webapp.py:436:0: C0206: Consider iterating with .items() (consider-using-dict-items)
  searx/webapp.py:950:4: C0206: Consider iterating with .items() (consider-using-dict-items)

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/preferences.py

@@ -179,7 +179,7 @@ class SearchLanguageSetting(EnumStringSetting):
         if data not in self.choices and data != self.value:  # pylint: disable=no-member
             # hack to give some backwards compatibility with old language cookies
             data = str(data).replace('_', '-')
-            lang = data.split('-')[0]
+            lang = data.split('-', maxsplit=1)[0]
             # pylint: disable=no-member
             if data in self.choices:
                 pass
@@ -503,6 +503,7 @@ class Preferences:
         """Save cookie in the HTTP reponse obect
         """
         for user_setting_name, user_setting in self.key_value_settings.items():
+            # pylint: disable=unnecessary-dict-index-lookup
             if self.key_value_settings[user_setting_name].locked:
                 continue
             user_setting.save(user_setting_name, resp)

searx/search/checker/__main__.py

@@ -34,8 +34,16 @@ else:
     BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = "", "", "", "", "", "", "", ""
 
 # equivalent of 'python -u' (unbuffered stdout, stderr)
-stdout = io.TextIOWrapper(open(sys.stdout.fileno(), 'wb', 0), write_through=True)
+stdout = io.TextIOWrapper(
-stderr = io.TextIOWrapper(open(sys.stderr.fileno(), 'wb', 0), write_through=True)
+    # pylint: disable=consider-using-with
+    open(sys.stdout.fileno(), 'wb', 0),
+    write_through=True
+)
+stderr = io.TextIOWrapper(
+    # pylint: disable=consider-using-with
+    open(sys.stderr.fileno(), 'wb', 0)
+    , write_through=True
+)
 
 
 # iterator of processors

searx/search/processors/__init__.py

@@ -17,7 +17,7 @@ __all__ = [
 import threading
 
 from searx import logger
-import searx.engines as engines
+from searx import engines
 
 from .online import OnlineProcessor
 from .offline import OfflineProcessor

searx/webapp.py

@@ -433,6 +433,7 @@ def _get_ordered_categories():
 def _get_enable_categories(all_categories):
     disabled_engines = request.preferences.engines.get_disabled()
     enabled_categories = set(
+        # pylint: disable=consider-using-dict-items
         category for engine_name in engines
         for category in engines[engine_name].categories
         if (engine_name, category) not in disabled_engines
@@ -947,7 +948,8 @@ def preferences():
     )
 
     engines_by_category = {}
-    for c in categories:
+
+    for c in categories: # pylint: disable=consider-using-dict-items
         engines_by_category[c] = [e for e in categories[c] if e.name in filtered_engines]
         # sort the engines alphabetically since the order in settings.yml is meaningless.
         list.sort(engines_by_category[c], key=lambda e: e.name)