blob: 51628e69ba0b6deae23fe91d9046bd2310c0c887 [file] [log] [blame]
Georg Brandl8ec7f652007-08-15 14:28:01 +00001
2:mod:`gettext` --- Multilingual internationalization services
3=============================================================
4
5.. module:: gettext
6 :synopsis: Multilingual internationalization services.
7.. moduleauthor:: Barry A. Warsaw <barry@zope.com>
8.. sectionauthor:: Barry A. Warsaw <barry@zope.com>
9
10
11The :mod:`gettext` module provides internationalization (I18N) and localization
12(L10N) services for your Python modules and applications. It supports both the
13GNU ``gettext`` message catalog API and a higher level, class-based API that may
14be more appropriate for Python files. The interface described below allows you
15to write your module and application messages in one natural language, and
16provide a catalog of translated messages for running under different natural
17languages.
18
19Some hints on localizing your Python modules and applications are also given.
20
21
22GNU :program:`gettext` API
23--------------------------
24
25The :mod:`gettext` module defines the following API, which is very similar to
26the GNU :program:`gettext` API. If you use this API you will affect the
27translation of your entire application globally. Often this is what you want if
28your application is monolingual, with the choice of language dependent on the
29locale of your user. If you are localizing a Python module, or if your
30application needs to switch languages on the fly, you probably want to use the
31class-based API instead.
32
33
34.. function:: bindtextdomain(domain[, localedir])
35
36 Bind the *domain* to the locale directory *localedir*. More concretely,
37 :mod:`gettext` will look for binary :file:`.mo` files for the given domain using
38 the path (on Unix): :file:`localedir/language/LC_MESSAGES/domain.mo`, where
39 *languages* is searched for in the environment variables :envvar:`LANGUAGE`,
40 :envvar:`LC_ALL`, :envvar:`LC_MESSAGES`, and :envvar:`LANG` respectively.
41
42 If *localedir* is omitted or ``None``, then the current binding for *domain* is
43 returned. [#]_
44
45
46.. function:: bind_textdomain_codeset(domain[, codeset])
47
48 Bind the *domain* to *codeset*, changing the encoding of strings returned by the
49 :func:`gettext` family of functions. If *codeset* is omitted, then the current
50 binding is returned.
51
52 .. versionadded:: 2.4
53
54
55.. function:: textdomain([domain])
56
57 Change or query the current global domain. If *domain* is ``None``, then the
58 current global domain is returned, otherwise the global domain is set to
59 *domain*, which is returned.
60
61
62.. function:: gettext(message)
63
64 Return the localized translation of *message*, based on the current global
65 domain, language, and locale directory. This function is usually aliased as
66 :func:`_` in the local namespace (see examples below).
67
68
69.. function:: lgettext(message)
70
71 Equivalent to :func:`gettext`, but the translation is returned in the preferred
72 system encoding, if no other encoding was explicitly set with
73 :func:`bind_textdomain_codeset`.
74
75 .. versionadded:: 2.4
76
77
78.. function:: dgettext(domain, message)
79
80 Like :func:`gettext`, but look the message up in the specified *domain*.
81
82
83.. function:: ldgettext(domain, message)
84
85 Equivalent to :func:`dgettext`, but the translation is returned in the preferred
86 system encoding, if no other encoding was explicitly set with
87 :func:`bind_textdomain_codeset`.
88
89 .. versionadded:: 2.4
90
91
92.. function:: ngettext(singular, plural, n)
93
94 Like :func:`gettext`, but consider plural forms. If a translation is found,
95 apply the plural formula to *n*, and return the resulting message (some
96 languages have more than two plural forms). If no translation is found, return
97 *singular* if *n* is 1; return *plural* otherwise.
98
99 The Plural formula is taken from the catalog header. It is a C or Python
100 expression that has a free variable *n*; the expression evaluates to the index
101 of the plural in the catalog. See the GNU gettext documentation for the precise
102 syntax to be used in :file:`.po` files and the formulas for a variety of
103 languages.
104
105 .. versionadded:: 2.3
106
107
108.. function:: lngettext(singular, plural, n)
109
110 Equivalent to :func:`ngettext`, but the translation is returned in the preferred
111 system encoding, if no other encoding was explicitly set with
112 :func:`bind_textdomain_codeset`.
113
114 .. versionadded:: 2.4
115
116
117.. function:: dngettext(domain, singular, plural, n)
118
119 Like :func:`ngettext`, but look the message up in the specified *domain*.
120
121 .. versionadded:: 2.3
122
123
124.. function:: ldngettext(domain, singular, plural, n)
125
126 Equivalent to :func:`dngettext`, but the translation is returned in the
127 preferred system encoding, if no other encoding was explicitly set with
128 :func:`bind_textdomain_codeset`.
129
130 .. versionadded:: 2.4
131
132Note that GNU :program:`gettext` also defines a :func:`dcgettext` method, but
133this was deemed not useful and so it is currently unimplemented.
134
135Here's an example of typical usage for this API::
136
137 import gettext
138 gettext.bindtextdomain('myapplication', '/path/to/my/language/directory')
139 gettext.textdomain('myapplication')
140 _ = gettext.gettext
141 # ...
142 print _('This is a translatable string.')
143
144
145Class-based API
146---------------
147
148The class-based API of the :mod:`gettext` module gives you more flexibility and
149greater convenience than the GNU :program:`gettext` API. It is the recommended
150way of localizing your Python applications and modules. :mod:`gettext` defines
151a "translations" class which implements the parsing of GNU :file:`.mo` format
152files, and has methods for returning either standard 8-bit strings or Unicode
153strings. Instances of this "translations" class can also install themselves in
154the built-in namespace as the function :func:`_`.
155
156
157.. function:: find(domain[, localedir[, languages[, all]]])
158
159 This function implements the standard :file:`.mo` file search algorithm. It
160 takes a *domain*, identical to what :func:`textdomain` takes. Optional
161 *localedir* is as in :func:`bindtextdomain` Optional *languages* is a list of
162 strings, where each string is a language code.
163
164 If *localedir* is not given, then the default system locale directory is used.
165 [#]_ If *languages* is not given, then the following environment variables are
166 searched: :envvar:`LANGUAGE`, :envvar:`LC_ALL`, :envvar:`LC_MESSAGES`, and
167 :envvar:`LANG`. The first one returning a non-empty value is used for the
168 *languages* variable. The environment variables should contain a colon separated
169 list of languages, which will be split on the colon to produce the expected list
170 of language code strings.
171
172 :func:`find` then expands and normalizes the languages, and then iterates
173 through them, searching for an existing file built of these components:
174
175 :file:`localedir/language/LC_MESSAGES/domain.mo`
176
177 The first such file name that exists is returned by :func:`find`. If no such
178 file is found, then ``None`` is returned. If *all* is given, it returns a list
179 of all file names, in the order in which they appear in the languages list or
180 the environment variables.
181
182
183.. function:: translation(domain[, localedir[, languages[, class_[, fallback[, codeset]]]]])
184
185 Return a :class:`Translations` instance based on the *domain*, *localedir*, and
186 *languages*, which are first passed to :func:`find` to get a list of the
187 associated :file:`.mo` file paths. Instances with identical :file:`.mo` file
188 names are cached. The actual class instantiated is either *class_* if provided,
189 otherwise :class:`GNUTranslations`. The class's constructor must take a single
190 file object argument. If provided, *codeset* will change the charset used to
191 encode translated strings.
192
193 If multiple files are found, later files are used as fallbacks for earlier ones.
194 To allow setting the fallback, :func:`copy.copy` is used to clone each
195 translation object from the cache; the actual instance data is still shared with
196 the cache.
197
198 If no :file:`.mo` file is found, this function raises :exc:`IOError` if
199 *fallback* is false (which is the default), and returns a
200 :class:`NullTranslations` instance if *fallback* is true.
201
202 .. versionchanged:: 2.4
203 Added the *codeset* parameter.
204
205
206.. function:: install(domain[, localedir[, unicode [, codeset[, names]]]])
207
208 This installs the function :func:`_` in Python's builtin namespace, based on
209 *domain*, *localedir*, and *codeset* which are passed to the function
210 :func:`translation`. The *unicode* flag is passed to the resulting translation
211 object's :meth:`install` method.
212
213 For the *names* parameter, please see the description of the translation
214 object's :meth:`install` method.
215
216 As seen below, you usually mark the strings in your application that are
217 candidates for translation, by wrapping them in a call to the :func:`_`
218 function, like this::
219
220 print _('This string will be translated.')
221
222 For convenience, you want the :func:`_` function to be installed in Python's
223 builtin namespace, so it is easily accessible in all modules of your
224 application.
225
226 .. versionchanged:: 2.4
227 Added the *codeset* parameter.
228
229 .. versionchanged:: 2.5
230 Added the *names* parameter.
231
232
233The :class:`NullTranslations` class
234^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
235
236Translation classes are what actually implement the translation of original
237source file message strings to translated message strings. The base class used
238by all translation classes is :class:`NullTranslations`; this provides the basic
239interface you can use to write your own specialized translation classes. Here
240are the methods of :class:`NullTranslations`:
241
242
243.. method:: NullTranslations.__init__([fp])
244
245 Takes an optional file object *fp*, which is ignored by the base class.
246 Initializes "protected" instance variables *_info* and *_charset* which are set
247 by derived classes, as well as *_fallback*, which is set through
248 :meth:`add_fallback`. It then calls ``self._parse(fp)`` if *fp* is not
249 ``None``.
250
251
252.. method:: NullTranslations._parse(fp)
253
254 No-op'd in the base class, this method takes file object *fp*, and reads the
255 data from the file, initializing its message catalog. If you have an
256 unsupported message catalog file format, you should override this method to
257 parse your format.
258
259
260.. method:: NullTranslations.add_fallback(fallback)
261
262 Add *fallback* as the fallback object for the current translation object. A
263 translation object should consult the fallback if it cannot provide a
264 translation for a given message.
265
266
267.. method:: NullTranslations.gettext(message)
268
269 If a fallback has been set, forward :meth:`gettext` to the fallback. Otherwise,
270 return the translated message. Overridden in derived classes.
271
272
273.. method:: NullTranslations.lgettext(message)
274
275 If a fallback has been set, forward :meth:`lgettext` to the fallback. Otherwise,
276 return the translated message. Overridden in derived classes.
277
278 .. versionadded:: 2.4
279
280
281.. method:: NullTranslations.ugettext(message)
282
283 If a fallback has been set, forward :meth:`ugettext` to the fallback. Otherwise,
284 return the translated message as a Unicode string. Overridden in derived
285 classes.
286
287
288.. method:: NullTranslations.ngettext(singular, plural, n)
289
290 If a fallback has been set, forward :meth:`ngettext` to the fallback. Otherwise,
291 return the translated message. Overridden in derived classes.
292
293 .. versionadded:: 2.3
294
295
296.. method:: NullTranslations.lngettext(singular, plural, n)
297
298 If a fallback has been set, forward :meth:`ngettext` to the fallback. Otherwise,
299 return the translated message. Overridden in derived classes.
300
301 .. versionadded:: 2.4
302
303
304.. method:: NullTranslations.ungettext(singular, plural, n)
305
306 If a fallback has been set, forward :meth:`ungettext` to the fallback.
307 Otherwise, return the translated message as a Unicode string. Overridden in
308 derived classes.
309
310 .. versionadded:: 2.3
311
312
313.. method:: NullTranslations.info()
314
315 Return the "protected" :attr:`_info` variable.
316
317
318.. method:: NullTranslations.charset()
319
320 Return the "protected" :attr:`_charset` variable.
321
322
323.. method:: NullTranslations.output_charset()
324
325 Return the "protected" :attr:`_output_charset` variable, which defines the
326 encoding used to return translated messages.
327
328 .. versionadded:: 2.4
329
330
331.. method:: NullTranslations.set_output_charset(charset)
332
333 Change the "protected" :attr:`_output_charset` variable, which defines the
334 encoding used to return translated messages.
335
336 .. versionadded:: 2.4
337
338
339.. method:: NullTranslations.install([unicode [, names]])
340
341 If the *unicode* flag is false, this method installs :meth:`self.gettext` into
342 the built-in namespace, binding it to ``_``. If *unicode* is true, it binds
343 :meth:`self.ugettext` instead. By default, *unicode* is false.
344
345 If the *names* parameter is given, it must be a sequence containing the names of
346 functions you want to install in the builtin namespace in addition to :func:`_`.
347 Supported names are ``'gettext'`` (bound to :meth:`self.gettext` or
348 :meth:`self.ugettext` according to the *unicode* flag), ``'ngettext'`` (bound to
349 :meth:`self.ngettext` or :meth:`self.ungettext` according to the *unicode*
350 flag), ``'lgettext'`` and ``'lngettext'``.
351
352 Note that this is only one way, albeit the most convenient way, to make the
353 :func:`_` function available to your application. Because it affects the entire
354 application globally, and specifically the built-in namespace, localized modules
355 should never install :func:`_`. Instead, they should use this code to make
356 :func:`_` available to their module::
357
358 import gettext
359 t = gettext.translation('mymodule', ...)
360 _ = t.gettext
361
362 This puts :func:`_` only in the module's global namespace and so only affects
363 calls within this module.
364
365 .. versionchanged:: 2.5
366 Added the *names* parameter.
367
368
369The :class:`GNUTranslations` class
370^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
371
372The :mod:`gettext` module provides one additional class derived from
373:class:`NullTranslations`: :class:`GNUTranslations`. This class overrides
374:meth:`_parse` to enable reading GNU :program:`gettext` format :file:`.mo` files
375in both big-endian and little-endian format. It also coerces both message ids
376and message strings to Unicode.
377
378:class:`GNUTranslations` parses optional meta-data out of the translation
379catalog. It is convention with GNU :program:`gettext` to include meta-data as
380the translation for the empty string. This meta-data is in :rfc:`822`\ -style
381``key: value`` pairs, and should contain the ``Project-Id-Version`` key. If the
382key ``Content-Type`` is found, then the ``charset`` property is used to
383initialize the "protected" :attr:`_charset` instance variable, defaulting to
384``None`` if not found. If the charset encoding is specified, then all message
385ids and message strings read from the catalog are converted to Unicode using
386this encoding. The :meth:`ugettext` method always returns a Unicode, while the
387:meth:`gettext` returns an encoded 8-bit string. For the message id arguments
388of both methods, either Unicode strings or 8-bit strings containing only
389US-ASCII characters are acceptable. Note that the Unicode version of the
390methods (i.e. :meth:`ugettext` and :meth:`ungettext`) are the recommended
391interface to use for internationalized Python programs.
392
393The entire set of key/value pairs are placed into a dictionary and set as the
394"protected" :attr:`_info` instance variable.
395
396If the :file:`.mo` file's magic number is invalid, or if other problems occur
397while reading the file, instantiating a :class:`GNUTranslations` class can raise
398:exc:`IOError`.
399
400The following methods are overridden from the base class implementation:
401
402
403.. method:: GNUTranslations.gettext(message)
404
405 Look up the *message* id in the catalog and return the corresponding message
406 string, as an 8-bit string encoded with the catalog's charset encoding, if
407 known. If there is no entry in the catalog for the *message* id, and a fallback
408 has been set, the look up is forwarded to the fallback's :meth:`gettext` method.
409 Otherwise, the *message* id is returned.
410
411
412.. method:: GNUTranslations.lgettext(message)
413
414 Equivalent to :meth:`gettext`, but the translation is returned in the preferred
415 system encoding, if no other encoding was explicitly set with
416 :meth:`set_output_charset`.
417
418 .. versionadded:: 2.4
419
420
421.. method:: GNUTranslations.ugettext(message)
422
423 Look up the *message* id in the catalog and return the corresponding message
424 string, as a Unicode string. If there is no entry in the catalog for the
425 *message* id, and a fallback has been set, the look up is forwarded to the
426 fallback's :meth:`ugettext` method. Otherwise, the *message* id is returned.
427
428
429.. method:: GNUTranslations.ngettext(singular, plural, n)
430
431 Do a plural-forms lookup of a message id. *singular* is used as the message id
432 for purposes of lookup in the catalog, while *n* is used to determine which
433 plural form to use. The returned message string is an 8-bit string encoded with
434 the catalog's charset encoding, if known.
435
436 If the message id is not found in the catalog, and a fallback is specified, the
437 request is forwarded to the fallback's :meth:`ngettext` method. Otherwise, when
438 *n* is 1 *singular* is returned, and *plural* is returned in all other cases.
439
440 .. versionadded:: 2.3
441
442
443.. method:: GNUTranslations.lngettext(singular, plural, n)
444
445 Equivalent to :meth:`gettext`, but the translation is returned in the preferred
446 system encoding, if no other encoding was explicitly set with
447 :meth:`set_output_charset`.
448
449 .. versionadded:: 2.4
450
451
452.. method:: GNUTranslations.ungettext(singular, plural, n)
453
454 Do a plural-forms lookup of a message id. *singular* is used as the message id
455 for purposes of lookup in the catalog, while *n* is used to determine which
456 plural form to use. The returned message string is a Unicode string.
457
458 If the message id is not found in the catalog, and a fallback is specified, the
459 request is forwarded to the fallback's :meth:`ungettext` method. Otherwise,
460 when *n* is 1 *singular* is returned, and *plural* is returned in all other
461 cases.
462
463 Here is an example::
464
465 n = len(os.listdir('.'))
466 cat = GNUTranslations(somefile)
467 message = cat.ungettext(
468 'There is %(num)d file in this directory',
469 'There are %(num)d files in this directory',
470 n) % {'num': n}
471
472 .. versionadded:: 2.3
473
474
475Solaris message catalog support
476^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
477
478The Solaris operating system defines its own binary :file:`.mo` file format, but
479since no documentation can be found on this format, it is not supported at this
480time.
481
482
483The Catalog constructor
484^^^^^^^^^^^^^^^^^^^^^^^
485
486.. index:: single: GNOME
487
488GNOME uses a version of the :mod:`gettext` module by James Henstridge, but this
489version has a slightly different API. Its documented usage was::
490
491 import gettext
492 cat = gettext.Catalog(domain, localedir)
493 _ = cat.gettext
494 print _('hello world')
495
496For compatibility with this older module, the function :func:`Catalog` is an
497alias for the :func:`translation` function described above.
498
499One difference between this module and Henstridge's: his catalog objects
500supported access through a mapping API, but this appears to be unused and so is
501not currently supported.
502
503
504Internationalizing your programs and modules
505--------------------------------------------
506
507Internationalization (I18N) refers to the operation by which a program is made
508aware of multiple languages. Localization (L10N) refers to the adaptation of
509your program, once internationalized, to the local language and cultural habits.
510In order to provide multilingual messages for your Python programs, you need to
511take the following steps:
512
513#. prepare your program or module by specially marking translatable strings
514
515#. run a suite of tools over your marked files to generate raw messages catalogs
516
517#. create language specific translations of the message catalogs
518
519#. use the :mod:`gettext` module so that message strings are properly translated
520
521In order to prepare your code for I18N, you need to look at all the strings in
522your files. Any string that needs to be translated should be marked by wrapping
523it in ``_('...')`` --- that is, a call to the function :func:`_`. For example::
524
525 filename = 'mylog.txt'
526 message = _('writing a log message')
527 fp = open(filename, 'w')
528 fp.write(message)
529 fp.close()
530
531In this example, the string ``'writing a log message'`` is marked as a candidate
532for translation, while the strings ``'mylog.txt'`` and ``'w'`` are not.
533
534The Python distribution comes with two tools which help you generate the message
535catalogs once you've prepared your source code. These may or may not be
536available from a binary distribution, but they can be found in a source
537distribution, in the :file:`Tools/i18n` directory.
538
539The :program:`pygettext` [#]_ program scans all your Python source code looking
540for the strings you previously marked as translatable. It is similar to the GNU
541:program:`gettext` program except that it understands all the intricacies of
542Python source code, but knows nothing about C or C++ source code. You don't
543need GNU ``gettext`` unless you're also going to be translating C code (such as
544C extension modules).
545
546:program:`pygettext` generates textual Uniforum-style human readable message
547catalog :file:`.pot` files, essentially structured human readable files which
548contain every marked string in the source code, along with a placeholder for the
549translation strings. :program:`pygettext` is a command line script that supports
550a similar command line interface as :program:`xgettext`; for details on its use,
551run::
552
553 pygettext.py --help
554
555Copies of these :file:`.pot` files are then handed over to the individual human
556translators who write language-specific versions for every supported natural
557language. They send you back the filled in language-specific versions as a
558:file:`.po` file. Using the :program:`msgfmt.py` [#]_ program (in the
559:file:`Tools/i18n` directory), you take the :file:`.po` files from your
560translators and generate the machine-readable :file:`.mo` binary catalog files.
561The :file:`.mo` files are what the :mod:`gettext` module uses for the actual
562translation processing during run-time.
563
564How you use the :mod:`gettext` module in your code depends on whether you are
565internationalizing a single module or your entire application. The next two
566sections will discuss each case.
567
568
569Localizing your module
570^^^^^^^^^^^^^^^^^^^^^^
571
572If you are localizing your module, you must take care not to make global
573changes, e.g. to the built-in namespace. You should not use the GNU ``gettext``
574API but instead the class-based API.
575
576Let's say your module is called "spam" and the module's various natural language
577translation :file:`.mo` files reside in :file:`/usr/share/locale` in GNU
578:program:`gettext` format. Here's what you would put at the top of your
579module::
580
581 import gettext
582 t = gettext.translation('spam', '/usr/share/locale')
583 _ = t.lgettext
584
585If your translators were providing you with Unicode strings in their :file:`.po`
586files, you'd instead do::
587
588 import gettext
589 t = gettext.translation('spam', '/usr/share/locale')
590 _ = t.ugettext
591
592
593Localizing your application
594^^^^^^^^^^^^^^^^^^^^^^^^^^^
595
596If you are localizing your application, you can install the :func:`_` function
597globally into the built-in namespace, usually in the main driver file of your
598application. This will let all your application-specific files just use
599``_('...')`` without having to explicitly install it in each file.
600
601In the simple case then, you need only add the following bit of code to the main
602driver file of your application::
603
604 import gettext
605 gettext.install('myapplication')
606
607If you need to set the locale directory or the *unicode* flag, you can pass
608these into the :func:`install` function::
609
610 import gettext
611 gettext.install('myapplication', '/usr/share/locale', unicode=1)
612
613
614Changing languages on the fly
615^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
616
617If your program needs to support many languages at the same time, you may want
618to create multiple translation instances and then switch between them
619explicitly, like so::
620
621 import gettext
622
623 lang1 = gettext.translation('myapplication', languages=['en'])
624 lang2 = gettext.translation('myapplication', languages=['fr'])
625 lang3 = gettext.translation('myapplication', languages=['de'])
626
627 # start by using language1
628 lang1.install()
629
630 # ... time goes by, user selects language 2
631 lang2.install()
632
633 # ... more time goes by, user selects language 3
634 lang3.install()
635
636
637Deferred translations
638^^^^^^^^^^^^^^^^^^^^^
639
640In most coding situations, strings are translated where they are coded.
641Occasionally however, you need to mark strings for translation, but defer actual
642translation until later. A classic example is::
643
644 animals = ['mollusk',
645 'albatross',
646 'rat',
647 'penguin',
648 'python',
649 ]
650 # ...
651 for a in animals:
652 print a
653
654Here, you want to mark the strings in the ``animals`` list as being
655translatable, but you don't actually want to translate them until they are
656printed.
657
658Here is one way you can handle this situation::
659
660 def _(message): return message
661
662 animals = [_('mollusk'),
663 _('albatross'),
664 _('rat'),
665 _('penguin'),
666 _('python'),
667 ]
668
669 del _
670
671 # ...
672 for a in animals:
673 print _(a)
674
675This works because the dummy definition of :func:`_` simply returns the string
676unchanged. And this dummy definition will temporarily override any definition
677of :func:`_` in the built-in namespace (until the :keyword:`del` command). Take
678care, though if you have a previous definition of :func:`_` in the local
679namespace.
680
681Note that the second use of :func:`_` will not identify "a" as being
682translatable to the :program:`pygettext` program, since it is not a string.
683
684Another way to handle this is with the following example::
685
686 def N_(message): return message
687
688 animals = [N_('mollusk'),
689 N_('albatross'),
690 N_('rat'),
691 N_('penguin'),
692 N_('python'),
693 ]
694
695 # ...
696 for a in animals:
697 print _(a)
698
699In this case, you are marking translatable strings with the function :func:`N_`,
700[#]_ which won't conflict with any definition of :func:`_`. However, you will
701need to teach your message extraction program to look for translatable strings
702marked with :func:`N_`. :program:`pygettext` and :program:`xpot` both support
703this through the use of command line switches.
704
705
706:func:`gettext` vs. :func:`lgettext`
707^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
708
709In Python 2.4 the :func:`lgettext` family of functions were introduced. The
710intention of these functions is to provide an alternative which is more
711compliant with the current implementation of GNU gettext. Unlike
712:func:`gettext`, which returns strings encoded with the same codeset used in the
713translation file, :func:`lgettext` will return strings encoded with the
714preferred system encoding, as returned by :func:`locale.getpreferredencoding`.
715Also notice that Python 2.4 introduces new functions to explicitly choose the
716codeset used in translated strings. If a codeset is explicitly set, even
717:func:`lgettext` will return translated strings in the requested codeset, as
718would be expected in the GNU gettext implementation.
719
720
721Acknowledgements
722----------------
723
724The following people contributed code, feedback, design suggestions, previous
725implementations, and valuable experience to the creation of this module:
726
727* Peter Funk
728
729* James Henstridge
730
731* Juan David Ibáñez Palomar
732
733* Marc-André Lemburg
734
735* Martin von Löwis
736
737* François Pinard
738
739* Barry Warsaw
740
741* Gustavo Niemeyer
742
743.. rubric:: Footnotes
744
745.. [#] The default locale directory is system dependent; for example, on RedHat Linux
746 it is :file:`/usr/share/locale`, but on Solaris it is :file:`/usr/lib/locale`.
747 The :mod:`gettext` module does not try to support these system dependent
748 defaults; instead its default is :file:`sys.prefix/share/locale`. For this
749 reason, it is always best to call :func:`bindtextdomain` with an explicit
750 absolute path at the start of your application.
751
752.. [#] See the footnote for :func:`bindtextdomain` above.
753
754.. [#] François Pinard has written a program called :program:`xpot` which does a
755 similar job. It is available as part of his :program:`po-utils` package at http
756 ://po-utils.progiciels-bpi.ca/.
757
758.. [#] :program:`msgfmt.py` is binary compatible with GNU :program:`msgfmt` except that
759 it provides a simpler, all-Python implementation. With this and
760 :program:`pygettext.py`, you generally won't need to install the GNU
761 :program:`gettext` package to internationalize your Python applications.
762
763.. [#] The choice of :func:`N_` here is totally arbitrary; it could have just as easily
764 been :func:`MarkThisStringForTranslation`.
765