locale/i18n: get default language and set it as early as possible

TODO elaborate xxxxx

electrum/gui/default_lang.py

@@ -0,0 +1,40 @@
+# Copyright (C) 2023 The Electrum developers
+# Distributed under the MIT software license, see the accompanying
+# file LICENCE or http://www.opensource.org/licenses/mit-license.php
+#
+# Note: try not to import modules from electrum, or at least from GUIs.
+#       This is to avoid evaluating module-level string-translations before we get
+#       a chance to set the default language.
+
+import os
+from typing import Optional
+
+from electrum.i18n import languages
+
+
+jLocale = None
+if "ANDROID_DATA" in os.environ:
+    from jnius import autoclass, cast
+    jLocale = autoclass("java.util.Locale")
+
+
+def get_default_language(*, gui_name: Optional[str] = None) -> str:
+    if gui_name == "qt":
+        from PyQt5.QtCore import QLocale
+        name = QLocale.system().name()
+        return name if name in languages else "en_UK"
+    elif gui_name == "qml":
+        from PyQt5.QtCore import QLocale
+        # On Android QLocale does not return the system locale
+        try:
+            name = str(jLocale.getDefault().toString())
+        except Exception:
+            name = QLocale.system().name()
+        return name if name in languages else "en_GB"
+    elif gui_name == "kivy":
+        if "ANDROID_DATA" not in os.environ:
+            return "en_UK"
+        # FIXME: CJK/Arabic/etc languages do not work at all with kivy due to font issues,
+        #        so it is easiest to just default to English... (see #2032)
+        return "en_UK"
+    return ""

electrum/gui/kivy/i18n.py

@@ -1,5 +1,10 @@
 import gettext
 
+from electrum.logging import get_logger
+
+
+_logger = get_logger(__name__)
+
 
 class _(str):
 
@@ -35,6 +40,7 @@ class _(str):
 
     @staticmethod
     def switch_lang(lang):
+        _logger.info(f"switch_lang() called with {lang=!r}")
         # get the right locales directory, and instantiate a gettext
         from electrum.i18n import LOCALE_DIR, set_language
         locales = gettext.translation('electrum', LOCALE_DIR, languages=[lang], fallback=True)

electrum/gui/kivy/util.py

@@ -1,4 +1,6 @@
-from kivy.utils import get_color_from_hex, platform
+from kivy.utils import get_color_from_hex
+
+from electrum.gui.default_lang import get_default_language as _get_default_language
 
 
 def address_colors(wallet, addr):
@@ -24,13 +26,4 @@ def address_colors(wallet, addr):
 
 
 def get_default_language() -> str:
-    if platform != 'android':
-        return 'en_UK'
-    # FIXME: CJK/Arabic/etc languages do not work at all with kivy due to font issues,
-    #        so it is easiest to just default to English... (see #2032)
-    return 'en_UK'
-    # # try getting the language of the Android OS
-    # from jnius import autoclass
-    # Locale = autoclass("java.util.Locale")
-    # lang = str(Locale.getDefault().toString())
-    # return lang if lang else 'en_UK'
+    return _get_default_language(gui_name="kivy")

electrum/gui/qml/__init__.py

@@ -33,9 +33,6 @@ if TYPE_CHECKING:
 
 from .qeapp import ElectrumQmlApplication, Exception_Hook
 
-if 'ANDROID_DATA' in os.environ:
-    from jnius import autoclass, cast
-    jLocale = autoclass("java.util.Locale")
 
 class ElectrumTranslator(QTranslator):
     def __init__(self, parent=None):
@@ -51,12 +48,6 @@ class ElectrumGui(BaseElectrumGui, Logger):
         BaseElectrumGui.__init__(self, config=config, daemon=daemon, plugins=plugins)
         Logger.__init__(self)
 
-        lang = config.get('language','')
-        if not lang:
-            lang = self.get_default_language()
-        self.logger.info(f'setting language {lang}')
-        set_language(lang)
-
         # uncomment to debug plugin and import tracing
         # os.environ['QML_IMPORT_TRACE'] = '1'
         # os.environ['QT_DEBUG_PLUGINS'] = '1'
@@ -119,12 +110,3 @@ class ElectrumGui(BaseElectrumGui, Logger):
     def stop(self):
         self.logger.info('closing GUI')
         self.app.quit()
-
-    def get_default_language(self):
-        # On Android QLocale does not return the system locale
-        try:
-            name = str(jLocale.getDefault().toString())
-        except Exception:
-            name = QLocale.system().name()
-        self.logger.info(f'System default locale: {name}')
-        return name if name in languages else 'en_GB'

electrum/gui/qt/__init__.py

@@ -65,7 +65,7 @@ from electrum.logging import Logger
 from electrum.gui import BaseElectrumGui
 
 from .installwizard import InstallWizard, WalletAlreadyOpenInMemory
-from .util import get_default_language, read_QIcon, ColorScheme, custom_message_box, MessageBoxMixin
+from .util import read_QIcon, ColorScheme, custom_message_box, MessageBoxMixin
 from .main_window import ElectrumWindow
 from .network_dialog import NetworkDialog
 from .stylesheet_patcher import patch_qt_stylesheet
@@ -111,7 +111,6 @@ class ElectrumGui(BaseElectrumGui, Logger):
 
     @profiler
     def __init__(self, *, config: 'SimpleConfig', daemon: 'Daemon', plugins: 'Plugins'):
-        set_language(config.get('language', get_default_language()))
         BaseElectrumGui.__init__(self, config=config, daemon=daemon, plugins=plugins)
         Logger.__init__(self)
         self.logger.info(f"Qt GUI starting up... Qt={QtCore.QT_VERSION_STR}, PyQt={QtCore.PYQT_VERSION_STR}")

electrum/gui/qt/util.py

@@ -1117,10 +1117,6 @@ class IconLabel(QWidget):
         self.icon.setPixmap(icon.pixmap(self.icon_size))
         self.icon.repaint()  # macOS hack for #6269
 
-def get_default_language():
-    name = QLocale.system().name()
-    return name if name in languages else 'en_UK'
-
 
 def char_width_in_lineedit() -> int:
     char_width = QFontMetrics(QLineEdit().font()).averageCharWidth()

run_electrum

@@ -384,14 +384,22 @@ def main():
         sys.exit(1)
 
     config = SimpleConfig(config_options)
+    cmdname = config.get('cmd')
 
     # set language as early as possible
     # Note: we are already too late for strings that are declared in the global scope
     #       of an already imported module. However, the GUI and the plugins at least have
-    #       not been imported yet.
-    # Note: it is ok to call set_language() again later. E.g. the Qt GUI has additional
-    #       tools to figure out the default language so it will get called again there.
-    set_language(config.get('language'))
+    #       not been imported yet. (see #4621)
+    # Note: it is ok to call set_language() again later, but note that any call only applies
+    #       to not-yet-evaluated strings.
+    if cmdname == 'gui':
+        from electrum.gui.default_lang import get_default_language
+        gui_name = config.get('gui', 'qt')
+        lang = config.get('language')
+        if not lang:
+            lang = get_default_language(gui_name=gui_name)
+            _logger.info(f"get_default_language: detected default as {lang=!r}")
+        set_language(lang)
 
     if config.get('testnet'):
         constants.set_testnet()
@@ -402,8 +410,6 @@ def main():
     elif config.get('signet'):
         constants.set_signet()
 
-    cmdname = config.get('cmd')
-
     if cmdname == 'daemon' and config.get("detach"):
         # detect lockfile.
         # This is not as good as get_file_descriptor, but that would require the asyncio loop