Documentation officielle de Python

21.1.1 GNU gettext API

The gettext module defines the following API, which is very similar to the GNU gettext API. If you use this API you will affect the translation of your entire application globally. Often this is what you want if your application is monolingual, with the choice of language dependent on the locale of your user. If you are localizing a Python module, or if your application needs to switch languages on the fly, you probably want to use the class-based API instead.

bindtextdomain( domain[, localedir]): Bind the domain to the locale directory localedir. More concretely, gettext will look for binary .mo files for the given domain using the path (on Unix): localedir/language/LC_MESSAGES/domain.mo, where languages is searched for in the environment variables LANGUAGE, LC_ALL, LC_MESSAGES, and LANG respectively.
If localedir is omitted or None, then the current binding for domain is returned.^21.1

bind_textdomain_codeset( domain[, codeset]): Bind the domain to codeset, changing the encoding of strings returned by the gettext() family of functions. If codeset is omitted, then the current binding is returned.
New in version 2.4.

textdomain( [domain]): Change or query the current global domain. If domain is None, then the current global domain is returned, otherwise the global domain is set to domain, which is returned.

gettext( message): Return the localized translation of message, based on the current global domain, language, and locale directory. This function is usually aliased as _ in the local namespace (see examples below).

lgettext( message): Equivalent to gettext(), but the translation is returned in the preferred system encoding, if no other encoding was explicitly set with bind_textdomain_codeset().
New in version 2.4.

dgettext( domain, message): Like gettext(), but look the message up in the specified domain.

ldgettext( domain, message): Equivalent to dgettext(), but the translation is returned in the preferred system encoding, if no other encoding was explicitly set with bind_textdomain_codeset().
New in version 2.4.

ngettext( singular, plural, n)

Like gettext(), but consider plural forms. If a translation is found, apply the plural formula to n, and return the resulting message (some languages have more than two plural forms). If no translation is found, return singular if n is 1; return plural otherwise.

The Plural formula is taken from the catalog header. It is a C or Python expression that has a free variable n; the expression evaluates to the index of the plural in the catalog. See the GNU gettext documentation for the precise syntax to be used in .po files, and the formulas for a variety of languages.

New in version 2.3.

lngettext( singular, plural, n): Equivalent to ngettext(), but the translation is returned in the preferred system encoding, if no other encoding was explicitly set with bind_textdomain_codeset().
New in version 2.4.

dngettext( domain, singular, plural, n): Like ngettext(), but look the message up in the specified domain.
New in version 2.3.

ldngettext( domain, singular, plural, n): Equivalent to dngettext(), but the translation is returned in the preferred system encoding, if no other encoding was explicitly set with bind_textdomain_codeset().
New in version 2.4.

Note that GNU gettext also defines a dcgettext() method, but this was deemed not useful and so it is currently unimplemented.

Here's an example of typical usage for this API:

import gettext
gettext.bindtextdomain('myapplication', '/path/to/my/language/directory')
gettext.textdomain('myapplication')
_ = gettext.gettext
# ...
print _('This is a translatable string.')

Footnotes

... returned.^21.1: The default locale directory is system dependent; for example, on RedHat Linux it is /usr/share/locale, but on Solaris it is /usr/lib/locale. The gettext module does not try to support these system dependent defaults; instead its default is sys.prefix/share/locale. For this reason, it is always best to call bindtextdomain() with an explicit absolute path at the start of your application.

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