translator objects now have the following search path:

    - selected locale messages in the tracker locale dir
    - selected locale messages in the system locale dir
    - english messages in the tracker locale dir
    - english messages in the system locale dir

automatically compile .mo files if needed (found .po file
and .mo is missing or .po mtime is greater that .mo mtime)

removed support for python < 2.0.  gettext module is now required.

get_translation: removed 'domain' argument, added 'tracker_home' argument

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 1.10 2004-07-14 07:27:21 a1s Exp $
+# $Id: i18n.py,v 1.11 2004-10-23 14:03:34 a1s Exp $
 
 """
 RoundUp Internationalization (I18N)
@@ -38,48 +38,19 @@
 __docformat__ = 'restructuredtext'
 
 import errno
+import gettext as gettext_module
+import os
+
+from roundup import msgfmt
 
 # 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 as gettext_module
-except ImportError:
-    gettext_module = None
-
-# use or emulate features of gettext_module
-if not gettext_module:
-    # no gettext engine available.
-    # implement emulation for Translations class
-    # and find_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 find_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"):
+if hasattr(gettext_module.GNUTranslations, "ngettext"):
+    # gettext_module has everything needed
+    RoundupNullTranslations = gettext_module.NullTranslations
+    RoundupTranslations = gettext_module.GNUTranslations
+else:
     # prior to 2.3, there was no plural forms.  mix simple emulation in
     class PluralFormsMixIn:
         def ngettext(self, singular, plural, count):
@@ -102,16 +73,84 @@ class RoundupTranslations(
         gettext_module.GNUTranslations, PluralFormsMixIn
     ):
         pass
-    # lookup function is available
-    find_translation = gettext_module.translation
-else:
-    # gettext_module has everything needed
-    RoundupNullTranslations = gettext_module.NullTranslations
-    RoundupTranslations = gettext_module.GNUTranslations
-    find_translation = gettext_module.translation
 
+def find_locales(language=None):
+    """Return normalized list of locale names to try for given language
+
+    If language is None, use OS environment variables as a starting point
 
-def get_translation(language=None, domain=DOMAIN,
+    """
+    # body of this function is borrowed from gettext_module.find()
+    if language is None:
+        languages = []
+        for envar in ('LANGUAGE', 'LC_ALL', 'LC_MESSAGES', 'LANG'):
+            val = os.environ.get(envar)
+            if val:
+                languages = val.split(':')
+                break
+    else:
+        languages = [language]
+    # now normalize and expand the languages
+    nelangs = []
+    for lang in languages:
+        for nelang in gettext_module._expand_lang(lang):
+            if nelang not in nelangs:
+                nelangs.append(nelang)
+    return nelangs
+
+def get_mofile(languages, localedir, domain=None):
+    """Return the first of .mo files found in localedir for languages
+
+    Parameters:
+        languages:
+            list of locale names to try
+        localedir:
+            path to directory containing locale files.
+            Usually this is either gettext_module._default_localedir
+            or 'locale' subdirectory in the tracker home.
+        domain:
+            optional name of messages domain.
+            If omitted or None, work with simplified
+            locale directory, as used in tracker homes:
+            message catalogs are kept in files locale.po
+            instead of locale/LC_MESSAGES/domain.po
+
+    Return the path of the first .mo file found.
+    If nothing found, return None.
+
+    Automatically compile .po files if necessary.
+
+    """
+    for locale in languages:
+        if locale == "C":
+            break
+        if domain:
+            basename = os.path.join(localedir, locale, "LC_MESSAGES", domain)
+        else:
+            basename = os.path.join(localedir, locale)
+        # look for message catalog files, check timestamps
+        mofile = basename + ".mo"
+        if os.path.isfile(mofile):
+            motime = os.path.getmtime(mofile)
+        else:
+            motime = 0
+        pofile = basename + ".po"
+        if os.path.isfile(pofile):
+            potime = os.path.getmtime(pofile)
+        else:
+            potime = 0
+        # see what we've found
+        if motime < potime:
+            # compile
+            msgfmt.make(pofile, mofile)
+        elif motime == 0:
+            # no files found - proceed to the next locale name
+            continue
+        # .mo file found or made
+        return mofile
+    return None
+
+def get_translation(language=None, tracker_home=None,
     translation_class=RoundupTranslations,
     null_translation_class=RoundupNullTranslations
 ):
@@ -120,51 +159,37 @@ def get_translation(language=None, domain=DOMAIN,
     Arguments 'translation_class' and 'null_translation_class'
     specify the classes that are instantiated for existing
     and non-existing translations, respectively.
+
     """
-    if language:
-        _languages = [language]
+    mofiles = []
+    # locale directory paths
+    system_locale = gettext_module._default_localedir
+    if tracker_home is not None:
+        tracker_locale = os.path.join(tracker_home, "locale")
     else:
-        # use OS environment
-        _languages = None
-    # except for english ("en") language, add english fallback if available
-    if language == "en":
-        _fallback = None
+        tracker_locale = None
+    # get the list of locales
+    locales = find_locales(language)
+    # add mofiles found in the tracker, then in the system locale directory
+    if tracker_locale:
+        mofiles.append(get_mofile(locales, tracker_locale))
+    mofiles.append(get_mofile(locales, system_locale, DOMAIN))
+    # we want to fall back to english unless english is selected language
+    if "en" not in locales:
+        locales = find_locales("en")
+        # add mofiles found in the tracker, then in the system locale directory
+        if tracker_locale:
+            mofiles.append(get_mofile(locales, tracker_locale))
+        mofiles.append(get_mofile(locales, system_locale, DOMAIN))
+    # filter out elements that are not found
+    mofiles = filter(None, mofiles)
+    if mofiles:
+        translator = translation_class(open(mofiles[0], "rb"))
+        for mofile in mofiles:
+            translator.add_fallback(translation_class(open(mofile, "rb")))
     else:
-        try:
-            _fallback = find_translation(domain=domain, languages=["en"],
-                class_=translation_class)
-            # gettext.translation returns a cached translation
-            # even if it is not of the desired class.
-            # This is a quick-and-dirty solution for this problem.
-            # It works with current codebase, because all translators
-            # inherit from respective base translation classes
-            # defined in the gettext module, i.e. have same internal data.
-            # The cached instance is not affected by this hack,
-            # 'cause gettext made a copy for us.
-            # XXX Consider making a copy of gettext.translation function
-            # with class bug fixed...
-            if _fallback.__class__ != translation_class:
-                _fallback.__class__ = translation_class
-        except IOError:
-            # no .mo files found
-            _fallback = None
-    # get the translation
-    try:
-        _translation = find_translation(domain=domain, languages=_languages,
-            class_=translation_class)
-        # XXX See the comment after first find_translation() call
-        if _translation.__class__ != translation_class:
-            _translation.__class__ = translation_class
-    except IOError:
-        _translation = None
-    # see what's found
-    if _translation and _fallback:
-        _translation.add_fallback(_fallback)
-    elif _fallback:
-        _translation = _fallback
-    elif not _translation:
-        _translation = null_translation_class()
-    return _translation
+        translator = null_translation_class()
+    return translator
 
 # static translations object
 translation = get_translation()