Refactor sphinx.locale

- Skip typing imports
- Simplify `translators`

sphinx/locale/__init__.py

@@ -1,11 +1,13 @@
 """Locale utilities."""
 
-import gettext
 import locale
-from collections import defaultdict
-from gettext import NullTranslations
+from gettext import NullTranslations, translation
 from os import path
-from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Union
+
+if False:
+    # NoQA
+    from collections.abc import Callable, Iterable
+    from typing import Any, Dict, List, Optional, Tuple, Union
 
 
 class _TranslationProxy:
@@ -37,7 +39,7 @@ def __str__(self) -> str:
     def __dir__(self) -> 'List[str]':
         return dir(str)
 
-    def __getattr__(self, name: str) -> Any:
+    def __getattr__(self, name: str) -> 'Any':
         return getattr(self.__str__(), name)
 
     def __getstate__(self) -> 'Tuple[Callable, Tuple[str, ...]]':
@@ -67,10 +69,10 @@ def __mod__(self, other: str) -> str:
     def __rmod__(self, other: str) -> str:
         return other % self.__str__()
 
-    def __mul__(self, other: Any) -> str:
+    def __mul__(self, other: 'Any') -> str:
         return self.__str__() * other
 
-    def __rmul__(self, other: Any) -> str:
+    def __rmul__(self, other: 'Any') -> str:
         return other * self.__str__()
 
     def __hash__(self):
@@ -92,11 +94,15 @@ def __getitem__(self, index):
         return self.__str__()[index]
 
 
-translators: Dict[Tuple[str, str], NullTranslations] = defaultdict(NullTranslations)
+translators: 'Dict[Tuple[str, str], NullTranslations]' = {}
 
 
-def init(locale_dirs: List[Optional[str]], language: Optional[str],
-         catalog: str = 'sphinx', namespace: str = 'general') -> Tuple[NullTranslations, bool]:
+def init(
+    locale_dirs: 'List[Optional[str]]',
+    language: 'Optional[str]',
+    catalog: str = 'sphinx',
+    namespace: str = 'general',
+) -> 'Tuple[NullTranslations, bool]':
     """Look for message catalogs in `locale_dirs` and *ensure* that there is at
     least a NullTranslations catalog set in `translators`. If called multiple
     times or if several ``.mo`` files are found, their contents are merged
@@ -112,7 +118,7 @@ def init(locale_dirs: List[Optional[str]], language: Optional[str],
 
     if language and '_' in language:
         # for language having country code (like "de_AT")
-        languages: Optional[List[str]] = [language, language.split('_')[0]]
+        languages: 'Optional[List[str]]' = [language, language.split('_')[0]]
     elif language:
         languages = [language]
     else:
@@ -121,7 +127,7 @@ def init(locale_dirs: List[Optional[str]], language: Optional[str],
     # loading
     for dir_ in locale_dirs:
         try:
-            trans = gettext.translation(catalog, localedir=dir_, languages=languages)
+            trans = translation(catalog, localedir=dir_, languages=languages)
             if translator is None:
                 translator = trans
             else:
@@ -137,7 +143,7 @@ def init(locale_dirs: List[Optional[str]], language: Optional[str],
     return translator, has_translation
 
 
-def setlocale(category: int, value: Union[str, Iterable[str], None] = None) -> None:
+def setlocale(category: int, value: 'Union[str, Iterable[str], None]' = None) -> None:
     """Update locale settings.
 
     This does not throw any exception even if update fails.
@@ -149,7 +155,7 @@ def setlocale(category: int, value: Union[str, Iterable[str], None] = None) -> N
     * https://bugs.python.org/issue18378#msg215215
 
     .. note:: Only for internal use.  Please don't call this method from extensions.
-              This will be removed in future.
+              This will be removed in Sphinx 6.0.
     """
     try:
         locale.setlocale(category, value)
@@ -158,9 +164,9 @@ def setlocale(category: int, value: Union[str, Iterable[str], None] = None) -> N
 
 
 def init_console(
-    locale_dir: str = path.abspath(path.dirname(__file__)),
+    locale_dir: str = path.abspath(path.dirname(__file__)),  # NoQA: B008
     catalog: str = 'sphinx',
-) -> Tuple[NullTranslations, bool]:
+) -> 'Tuple[NullTranslations, bool]':
     """Initialize locale for console.
 
     .. versionadded:: 1.8
@@ -176,7 +182,7 @@ def init_console(
 
 
 def get_translator(catalog: str = 'sphinx', namespace: str = 'general') -> NullTranslations:
-    return translators[(namespace, catalog)]
+    return translators.get((namespace, catalog), NullTranslations())
 
 
 def is_translator_registered(catalog: str = 'sphinx', namespace: str = 'general') -> bool:
@@ -191,7 +197,7 @@ def _lazy_translate(catalog: str, namespace: str, message: str) -> str:
     return translator.gettext(message)
 
 
-def get_translation(catalog: str, namespace: str = 'general') -> Callable[[str], str]:
+def get_translation(catalog: str, namespace: str = 'general') -> 'Callable[[str], str]':
     """Get a translation function based on the *catalog* and *namespace*.
 
     The extension can use this API to translate the messages on the
@@ -216,7 +222,7 @@ def setup(app):
 
     .. versionadded:: 1.8
     """
-    def gettext(message: str, *args: Any) -> str:
+    def gettext(message: str, *args: 'Any') -> str:
         if not is_translator_registered(catalog, namespace):
             # not initialized yet
             return _TranslationProxy(_lazy_translate, catalog, namespace, message)  # type: ignore  # NOQA
@@ -254,7 +260,7 @@ def gettext(message: str, *args: Any) -> str:
 }
 
 # Moved to sphinx.directives.other (will be overridden later)
-versionlabels: Dict[str, str] = {}
+versionlabels: 'Dict[str, str]' = {}
 
 # Moved to sphinx.domains.python (will be overridden later)
-pairindextypes: Dict[str, str] = {}
+pairindextypes: 'Dict[str, str]' = {}