export unicode functions and DOMAIN name;

added ngettext emulation for earlier python versions (2.1, 2.2);

added get_translation() function to find different translations at runtime

Author: Alexander Smishlajev

roundup/i18n.py

@@ -15,7 +15,7 @@
 # BASIS, AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
 # SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 #
-# $Id: i18n.py,v 1.6 2004-05-18 19:20:47 a1s Exp $
+# $Id: i18n.py,v 1.7 2004-05-22 14:40:17 a1s Exp $
 
 """
 RoundUp Internationalization (I18N)
@@ -37,21 +37,115 @@
 """
 __docformat__ = 'restructuredtext'
 
+import errno
+
+# Roundup text domain
+DOMAIN = "roundup"
+
 # first, we try to import gettext; this probably never fails, but we make
 # sure we survive this anyway
 try:
-    import gettext
+    import gettext as gettext_module
 except ImportError:
-    # fall-back to dummy on errors (returning the english text)
-    _ = gettext = lambda text: text
-    def ngettext(singular, plural, count):
-        if count == 1: return singular
-        return plural
+    gettext_module = None
+
+# use or emulate features of gettext_module
+if not gettext_module:
+    # no gettext engine available.
+    # implement emulation for Translations class
+    # and translation() function
+    class RoundupNullTranslations:
+        """Dummy Translations class
+
+        Only methods used by Roundup are implemented.
+
+        """
+        def add_fallback(self, fallback):
+            pass
+        def gettext(self, text):
+            return text
+        def ugettext(self, text):
+            return unicode(text)
+        def ngettext(self, singular, plural, count):
+            if count == 1: return singular
+            return plural
+        def ungettext(self, singular, plural, count):
+            return unicode(self.ngettext(singular, plural, count))
+
+    RoundupTranslations = RoundupNullTranslations
+
+    def translation(domain, localedir=None, languages=None, class_=None):
+        """Always raise IOError (no message catalogs available)"""
+        raise IOError(errno.ENOENT,
+            "No translation file found for domain", domain)
+
+elif not hasattr(gettext_module.GNUTranslations, "ngettext"):
+    # prior to 2.3, there was no plural forms.  mix simple emulation in
+    class PluralFormsMixIn:
+        def ngettext(self, singular, plural, count):
+            if count == 1:
+                _msg = singular
+            else:
+                _msg = plural
+            return self.gettext(_msg)
+        def ngettext(self, singular, plural, count):
+            if count == 1:
+                _msg = singular
+            else:
+                _msg = plural
+            return self.gettext(_msg)
+    class RoundupNullTranslations(
+        gettext_module.NullTranslations, PluralFormsMixIn
+    ):
+        pass
+    class RoundupTranslations(
+        gettext_module.GNUTranslations, PluralFormsMixIn
+    ):
+        pass
+    # lookup function is available
+    translation = gettext_module.translation
 else:
-    # use roundup messages
-    gettext.textdomain("roundup")
-    # export gettext functions
-    ngettext = gettext.ngettext
-    _ = gettext = gettext.gettext
+    # gettext_module has everything needed
+    RoundupNullTranslations = gettext_module.NullTranslations
+    RoundupTranslations = gettext_module.GNUTranslations
+    translation = gettext_module.translation
+
+
+def get_translation(language=None, domain=DOMAIN):
+    """Return Translation object for given language and domain"""
+    if language:
+        _languages = [language]
+    else:
+        # use OS environment
+        _languages = None
+    # except for english ("en") language, add english fallback if available
+    try:
+        _fallback = translation(domain=domain, languages=["en"],
+            class_=RoundupTranslations)
+    except IOError:
+        # no .mo files found
+        _fallback = None
+    # get the translation
+    try:
+        _translation = translation(domain=domain, languages=_languages,
+            class_=RoundupTranslations)
+    except IOError:
+        _translation = None
+    # see what's found
+    if _translation and _fallback:
+        _translation.add_fallback(_fallback)
+    elif _fallback:
+        _translation = _fallback
+    elif not _translation:
+        _translation = RoundupNullTranslations()
+    return _translation
+
+# static translations object
+translation = get_translation()
+# static translation functions
+_ = gettext = translation.gettext
+ugettext = translation.ugettext
+ngettext = translation.ngettext
+ungettext = translation.ungettext
 
-# vim: set filetype=python ts=4 sw=4 et si
+# vim: set filetype=python sts=4 sw=4 et si