Finalize this module for Python 2.0 based on feedback and input from

Martin von Loewis, Peter Funk, James Henstridge, Francois Pinard, and
Marc-Andre Lemburg.
This commit is contained in:
Barry Warsaw 2000-08-30 03:29:58 +00:00
parent 28b815f28a
commit 33d8d705b8
1 changed files with 141 additions and 174 deletions

View File

@ -6,83 +6,7 @@ message catalog library.
I18N refers to the operation by which a program is made aware of multiple
languages. L10N refers to the adaptation of your program, once
internationalized, to the local language and cultural habits. In order to
provide multilingual messages for your Python programs, you need to take the
following steps:
- prepare your program by specially marking translatable strings
- run a suite of tools over your marked program files to generate raw
messages catalogs
- create language specific translations of the message catalogs
- use this module so that message strings are properly translated
In order to prepare your program for I18N, you need to look at all the strings
in your program. Any string that needs to be translated should be marked by
wrapping it in _('...') -- i.e. a call to the function `_'. For example:
filename = 'mylog.txt'
message = _('writing a log message')
fp = open(filename, 'w')
fp.write(message)
fp.close()
In this example, the string `writing a log message' is marked as a candidate
for translation, while the strings `mylog.txt' and `w' are not.
The GNU gettext package provides a tool, called xgettext, that scans C and C++
source code looking for these specially marked strings. xgettext generates
what are called `.pot' files, essentially structured human readable files
which contain every marked string in the source code. These .pot files are
copied and handed over to translators who write language-specific versions for
every supported language.
For I18N Python programs however, xgettext won't work; it doesn't understand
the myriad of string types support by Python. The standard Python
distribution provides a tool called pygettext that does though (found in the
Tools/i18n directory). This is a command line script that supports a similar
interface as xgettext; see its documentation for details. Once you've used
pygettext to create your .pot files, you can use the standard GNU gettext
tools to generate your machine-readable .mo files, which are what's used by
this module.
In the simple case, to use this module then, you need only add the following
bit of code to the main driver file of your application:
import gettext
gettext.install()
This sets everything up so that your _('...') function calls Just Work. In
other words, it installs `_' in the builtins namespace for convenience. You
can skip this step and do it manually by the equivalent code:
import gettext
import __builtin__
__builtin__['_'] = gettext.gettext
Once you've done this, you probably want to call bindtextdomain() and
textdomain() to get the domain set up properly. Again, for convenience, you
can pass the domain and localedir to install to set everything up in one fell
swoop:
import gettext
gettext.install('mydomain', '/my/locale/dir')
If your program needs to support many languages at the same time, you will
want to create Translation objects explicitly, like so:
import gettext
gettext.install()
lang1 = gettext.Translations(open('/path/to/my/lang1/messages.mo'))
lang2 = gettext.Translations(open('/path/to/my/lang2/messages.mo'))
lang3 = gettext.Translations(open('/path/to/my/lang3/messages.mo'))
gettext.set(lang1)
# all _() will now translate to language 1
gettext.set(lang2)
# all _() will now translate to language 2
Currently, only GNU gettext format binary .mo files are supported.
internationalized, to the local language and cultural habits.
"""
@ -104,21 +28,27 @@ Currently, only GNU gettext format binary .mo files are supported.
#
# Barry Warsaw integrated these modules, wrote the .install() API and code,
# and conformed all C and Python code to Python's coding standards.
#
# Francois Pinard and Marc-Andre Lemburg also contributed valuably to this
# module.
#
# TODO:
# - Lazy loading of .mo files. Currently the entire catalog is loaded into
# memory, but that's probably bad for large translated programs. Instead,
# the lexical sort of original strings in GNU .mo files should be exploited
# to do binary searches and lazy initializations. Or you might want to use
# the undocumented double-hash algorithm for .mo files with hash tables, but
# you'll need to study the GNU gettext code to do this.
#
# - Support Solaris .mo file formats. Unfortunately, we've been unable to
# find this format documented anywhere.
import os
import sys
import struct
from UserDict import UserDict
from errno import ENOENT
# globals
_translations = {}
_current_translation = None
_current_domain = 'messages'
# Domain to directory mapping, for use by bindtextdomain()
_localedirs = {}
_default_localedir = os.path.join(sys.prefix, 'share', 'locale')
@ -165,16 +95,37 @@ def _expand_lang(locale):
class GNUTranslations(UserDict):
# Magic number of .mo files
MAGIC = 0x950412de
class NullTranslations:
def __init__(self, fp=None):
self._info = {}
self._charset = None
if fp:
self._parse(fp)
def __init__(self, fp):
if fp is None:
d = {}
else:
d = self._parse(fp)
UserDict.__init__(self, d)
def _parse(self, fp):
pass
def gettext(self, message):
return message
def ugettext(self, message):
return unicode(message)
def info(self):
return self._info
def charset(self):
return self._charset
def install(self, unicode=0):
import __builtin__
__builtin__.__dict__['_'] = unicode and self.ugettext or self.gettext
class GNUTranslations(NullTranslations):
# Magic number of .mo files
LE_MAGIC = 0x950412de
BE_MAGIC = struct.unpack('>i', struct.pack('<i', LE_MAGIC))[0]
def _parse(self, fp):
"""Override this method to support alternative .mo formats."""
@ -182,51 +133,62 @@ class GNUTranslations(UserDict):
filename = getattr(fp, 'name', '')
# Parse the .mo file header, which consists of 5 little endian 32
# bit words.
catalog = {}
self._catalog = catalog = {}
buf = fp.read()
magic, version, msgcount, masteridx, transidx = unpack(
'<5i', buf[:20])
if magic <> self.MAGIC:
# Are we big endian or little endian?
magic = unpack('<i', buf[:4])[0]
if magic == self.LE_MAGIC:
version, msgcount, masteridx, transidx = unpack('<4i', buf[4:20])
ii = '<ii'
elif magic == self.BE_MAGIC:
version, msgcount, masteridx, transidx = unpack('>4i', buf[4:20])
ii = '>ii'
else:
raise IOError(0, 'Bad magic number', filename)
#
# Now put all messages from the .mo file buffer into the catalog
# dictionary.
for i in xrange(0, msgcount):
mstart = unpack('<i', buf[masteridx+4:masteridx+8])[0]
mend = mstart + unpack('<i', buf[masteridx:masteridx+4])[0]
tstart = unpack('<i', buf[transidx+4:transidx+8])[0]
tend = tstart + unpack('<i', buf[transidx:transidx+4])[0]
mlen, moff = unpack(ii, buf[masteridx:masteridx+8])
mend = moff + mlen
tlen, toff = unpack(ii, buf[transidx:transidx+8])
tend = toff + tlen
if mend < len(buf) and tend < len(buf):
catalog[buf[mstart:mend]] = buf[tstart:tend]
tmsg = buf[toff:tend]
catalog[buf[moff:mend]] = tmsg
else:
raise IOError(0, 'File is corrupt', filename)
#
# See if we're looking at GNU .mo conventions for metadata
if mlen == 0 and tmsg.lower().startswith('project-id-version:'):
# Catalog description
for item in tmsg.split('\n'):
item = item.strip()
if not item:
continue
k, v = item.split(':', 1)
k = k.strip().lower()
v = v.strip()
self._info[k] = v
if k == 'content-type':
self._charset = v.split('charset=')[1]
# advance to next entry in the seek tables
masteridx += 8
transidx += 8
return catalog
def gettext(self, message):
return self._catalog.get(message, message)
def ugettext(self, message):
tmsg = self._catalog.get(message, message)
return unicode(tmsg, self._charset)
# By default, use GNU gettext format .mo files
Translations = GNUTranslations
# Locate a .mo file using the gettext strategy
def _find(localedir=None, languages=None, domain=None):
global _current_domain
global _localedirs
def find(domain, localedir=None, languages=None):
# Get some reasonable defaults for arguments that were not supplied
if domain is None:
domain = _current_domain
if localedir is None:
localedir = _localedirs.get(
domain,
# TBD: The default localedir is actually system dependent. I
# don't know of a good platform-consistent and portable way to
# default it, so instead, we'll just use sys.prefix. Most
# programs should be calling bindtextdomain() or such explicitly
# anyway.
os.path.join(sys.prefix, 'share', 'locale'))
localedir = _default_localedir
if languages is None:
languages = []
for envar in ('LANGUAGE', 'LC_ALL', 'LC_MESSAGES', 'LANG'):
@ -247,72 +209,77 @@ def _find(localedir=None, languages=None, domain=None):
if lang == 'C':
break
mofile = os.path.join(localedir, lang, 'LC_MESSAGES', '%s.mo' % domain)
# see if it's in the cache
mo = _translations.get(mofile)
if mo:
return mo
fp = None
try:
try:
fp = open(mofile, 'rb')
t = Translations(fp)
_translations[mofile] = t
return t
except IOError:
pass
finally:
if fp:
fp.close()
return {}
if os.path.exists(mofile):
return mofile
return None
def bindtextdomain(domain=None, localedir=None):
"""Bind domain to a file in the specified directory."""
global _localedirs
if domain is None:
return None
if localedir is None:
return _localedirs.get(domain, _localedirs.get('C'))
_localedirs[domain] = localedir
return localedir
# a mapping between absolute .mo file path and Translation object
_translations = {}
def translation(domain, localedir=None, languages=None, class_=None):
if class_ is None:
class_ = GNUTranslations
mofile = find(domain, localedir, languages)
if mofile is None:
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?
t = _translations.setdefault(key, class_(open(mofile, 'rb')))
return t
def install(domain, localedir=None, unicode=0):
translation(domain, localedir).install(unicode)
# a mapping b/w domains and locale directories
_localedirs = {}
# current global domain, `messages' used for compatibility w/ GNU gettext
_current_domain = 'messages'
def textdomain(domain=None):
"""Change or query the current global domain."""
global _current_domain
if domain is None:
return _current_domain
else:
if domain is not None:
_current_domain = domain
return domain
return _current_domain
def gettext(message):
"""Return localized version of a message."""
return _find().get(message, message)
def bindtextdomain(domain, localedir=None):
global _localedirs
if localedir is not None:
_localedirs[domain] = localedir
return _localedirs.get(domain, _default_localedir)
def dgettext(domain, message):
"""Like gettext(), but look up message in specified domain."""
return _find(domain=domain).get(message, message)
try:
t = translation(domain, _localedirs.get(domain, None))
except IOError:
return message
return t.gettext(message)
def gettext(message):
return dgettext(_current_domain, message)
# A higher level API
def set(translation):
global _current_translation
_current_translation = translation
# dcgettext() has been deemed unnecessary and is not implemented.
# James Henstridge's Catalog constructor from GNOME gettext. Documented usage
# was:
#
# import gettext
# cat = gettext.Catalog(PACKAGE, localedir=LOCALEDIR)
# _ = cat.gettext
# print _('Hello World')
def get():
global _current_translation
return _current_translation
# The resulting catalog object currently don't support access through a
# dictionary API, which was supported (but apparently unused) in GNOME
# gettext.
def install(domain=None, localedir=None):
import __builtin__
__builtin__.__dict__['_'] = gettext
if domain is not None:
bindtextdomain(domain, localedir)
textdomain(domain)
Catalog = translation