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