Add a per-message fallback mechanism for translations.
diff --git a/Doc/lib/libgettext.tex b/Doc/lib/libgettext.tex
index be22340..c19d9b9 100644
--- a/Doc/lib/libgettext.tex
+++ b/Doc/lib/libgettext.tex
@@ -95,7 +95,8 @@
Translations instances can also install themselves in the built-in
namespace as the function \function{_()}.
-\begin{funcdesc}{find}{domain\optional{, localedir\optional{, languages}}}
+\begin{funcdesc}{find}{domain\optional{, localedir\optional{,
+ languages\optional{, all}}}}
This function implements the standard \file{.mo} file search
algorithm. It takes a \var{domain}, identical to what
\function{textdomain()} takes. Optional \var{localedir} is as in
@@ -119,7 +120,9 @@
\file{\var{localedir}/\var{language}/LC_MESSAGES/\var{domain}.mo}
The first such file name that exists is returned by \function{find()}.
-If no such file is found, then \code{None} is returned.
+If no such file is found, then \code{None} is returned. If \var{all}
+is given, it returns a list of all file names, in the order in which
+they appear in the languages list or the environment variables.
\end{funcdesc}
\begin{funcdesc}{translation}{domain\optional{, localedir\optional{,
@@ -127,15 +130,22 @@
class_,\optional{fallback}}}}}
Return a \class{Translations} instance based on the \var{domain},
\var{localedir}, and \var{languages}, which are first passed to
-\function{find()} to get the
-associated \file{.mo} file path. Instances with
+\function{find()} to get a list of the
+associated \file{.mo} file paths. Instances with
identical \file{.mo} file names are cached. The actual class instantiated
is either \var{class_} if provided, otherwise
\class{GNUTranslations}. The class's constructor must take a single
-file object argument. If no \file{.mo} file is found, this
-function raises \exception{IOError} if \var{fallback} is false
-(which is the default), and returns a \class{NullTranslations} instance
-if \var{fallback} is true.
+file object argument.
+
+If multiple files are found, later files are used as fallbacks for
+earlier ones. To allow setting the fallback, \function{copy.copy}
+is used to clone each translation object from the cache; the actual
+instance data is still shared with the cache.
+
+If no \file{.mo} file is found, this function raises
+\exception{IOError} if \var{fallback} is false (which is the default),
+and returns a \class{NullTranslations} instance if \var{fallback} is
+true.
\end{funcdesc}
\begin{funcdesc}{install}{domain\optional{, localedir\optional{, unicode}}}
@@ -168,7 +178,8 @@
\begin{methoddesc}[NullTranslations]{__init__}{\optional{fp}}
Takes an optional file object \var{fp}, which is ignored by the base
class. Initializes ``protected'' instance variables \var{_info} and
-\var{_charset} which are set by derived classes. It then calls
+\var{_charset} which are set by derived classes, as well as \var{_fallback},
+which is set through \method{add_fallback}. It then calls
\code{self._parse(fp)} if \var{fp} is not \code{None}.
\end{methoddesc}
@@ -179,13 +190,21 @@
override this method to parse your format.
\end{methoddesc}
+\begin{methoddesc}{NullTranslations}{add_fallback}{fallback}
+Add \var{fallback} as the fallback object for the current translation
+object. A translation object should consult the fallback if it cannot
+provide a translation for a given message.
+\end{methoddesc}
+
\begin{methoddesc}[NullTranslations]{gettext}{message}
-Return the translated message. Overridden in derived classes.
+If a fallback has been set, forward \method{gettext} to the fallback.
+Otherwise, return the translated message. Overridden in derived classes.
\end{methoddesc}
\begin{methoddesc}[NullTranslations]{ugettext}{message}
-Return the translated message as a Unicode string. Overridden in
-derived classes.
+If a fallback has been set, forward \method{ugettext} to the fallback.
+Otherwise, return the translated message as a Unicode string.
+Overridden in derived classes.
\end{methoddesc}
\begin{methoddesc}[NullTranslations]{info}{}
diff --git a/Lib/gettext.py b/Lib/gettext.py
index 6795ee6..0bea9ed 100644
--- a/Lib/gettext.py
+++ b/Lib/gettext.py
@@ -46,6 +46,7 @@
import os
import sys
import struct
+import copy
from errno import ENOENT
__all__ = ["bindtextdomain","textdomain","gettext","dgettext",
@@ -102,16 +103,27 @@
def __init__(self, fp=None):
self._info = {}
self._charset = None
+ self._fallback = None
if fp:
self._parse(fp)
def _parse(self, fp):
pass
+ def add_fallback(self, fallback):
+ if self._fallback:
+ self._fallback.add_fallback(fallback)
+ else:
+ self._fallback = fallback
+
def gettext(self, message):
+ if self._fallback:
+ return self._fallback.gettext(message)
return message
def ugettext(self, message):
+ if self._fallback:
+ return self._fallback.ugettext(message)
return unicode(message)
def info(self):
@@ -188,16 +200,26 @@
transidx += 8
def gettext(self, message):
- return self._catalog.get(message, message)
+ try:
+ return self._catalog[message]
+ except KeyError:
+ if self._fallback:
+ return self._fallback.gettext(message)
+ return message
def ugettext(self, message):
- tmsg = self._catalog.get(message, message)
+ try:
+ tmsg = self._catalog[message]
+ except KeyError:
+ if self._fallback:
+ return self._fallback.ugettext(message)
+ tmsg = message
return unicode(tmsg, self._charset)
# Locate a .mo file using the gettext strategy
-def find(domain, localedir=None, languages=None):
+def find(domain, localedir=None, languages=None, all=0):
# Get some reasonable defaults for arguments that were not supplied
if localedir is None:
localedir = _default_localedir
@@ -217,13 +239,20 @@
if nelang not in nelangs:
nelangs.append(nelang)
# select a language
+ if all:
+ result = []
+ else:
+ result = None
for lang in nelangs:
if lang == 'C':
break
mofile = os.path.join(localedir, lang, 'LC_MESSAGES', '%s.mo' % domain)
if os.path.exists(mofile):
- return mofile
- return None
+ if all:
+ result.append(mofile)
+ else:
+ return mofile
+ return result
@@ -234,20 +263,28 @@
class_=None, fallback=0):
if class_ is None:
class_ = GNUTranslations
- mofile = find(domain, localedir, languages)
- if mofile is None:
+ mofiles = find(domain, localedir, languages, all=1)
+ if len(mofiles)==0:
if fallback:
return NullTranslations()
raise IOError(ENOENT, 'No translation file found for domain', domain)
- key = os.path.abspath(mofile)
# TBD: do we need to worry about the file pointer getting collected?
# Avoid opening, reading, and parsing the .mo file after it's been done
# once.
- t = _translations.get(key)
- if t is None:
- t = _translations.setdefault(key, class_(open(mofile, 'rb')))
- return t
-
+ result = None
+ for mofile in mofiles:
+ key = os.path.abspath(mofile)
+ t = _translations.get(key)
+ if t is None:
+ t = _translations.setdefault(key, class_(open(mofile, 'rb')))
+ # Copy the translation object to allow setting fallbacks.
+ # All other instance data is shared with the cached object.
+ t = copy.copy(t)
+ if result is None:
+ result = t
+ else:
+ result.add_fallback(t)
+ return result
def install(domain, localedir=None, unicode=0):
diff --git a/Misc/NEWS b/Misc/NEWS
index cc81150..355c926 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -26,7 +26,9 @@
arbitrary shell code can't be executed because a bogus URL was
passed in.
-- gettext.translation has an optional fallback argument.
+- gettext.translation has an optional fallback argument, and
+ gettext.find an optional all argument. Translations will now fallback
+ on a per-message basis.
Tools/Demos