Locale::gettext

version 1.07

This is a Perl5 module quickly written to gain access to the C library functions for internatialization. They work just like the C versions of the "GNU gettext utilities."

As of version 1.04, an object-oriented interface more suitable to native Perl programs is available.

Locale::gettext is Copyright 1996–2005 by Kim Vandry [email protected]. All rights reserved.

This library is free software; you may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file.

Changes

1.07

Fix test failures caused by $LANGUAGE being set

1.06

Bugfix: #104667 Makefile.PL libaries need to be listed after .o files

Bugfix: #104668 ensure availability of locale API, correct typo in documentation

Add META.yml (Fixes #91921)

1.05

Bugfix: [cpan #13042] useless #ifdef should be #if

Bugfix: [cpan #13044] make test fails when using POSIX locale

1.04

Add several functions provided by the GNU gettext library

Create object oriented interface

1.03

Fix error in README file

1.02

Include a License

1.01

Changed from gettext to Locale::gettext (i.e. moved under Locale::) on the advice of several people

Small "lint" fix from [email protected]

1.00

Initial version

TODO

A TIEHASH interface

Here's a quick tutorial.

Note that your vendor's implementation of these functions may be a bit different, but I think that in general these are quite standard POSIX functions.

Kim Vandry [email protected], Mlink Internet http://www.Mlink.NET, July 1996

INTERNATIONALIZING YOUR PROGRAM

Step 1

If you've already written your code, you need to wrap the gettext() function around all of the text strings. Needless to say, this is much easier if you do it while you write.

# create object for oo interface
my $d = Locale::gettext->domain("my_program");

print "Welcome to my program\n";

# oo
print $d->get("Welcome to my program"), "\n";

# traditional
print gettext("Welcome to my program"), "\n";

Note that you probably don't want to include that newline in the gettext() call, nor any formatting codes such as HTML tags. The argument to gettext() is the text string in the default language or locale. This is known as the C locale and should probably be usually English.

Step 2

Do the apropriate initializations at the beginning of your program:

use POSIX;     # for setlocale()
use Locale::gettext;

The following statement initializes the locale handling code in the C library. Normally, it causes it to read in the environment variables that determine the current locale.

The first parameter is the category you would like to initialize locale information for. You can use LC_ALL for this, which will set locale information for all categories, including LC_CTYPE, LC_TIME, LC_NUMERIC, etc.

I recommend that you set only LC_MESSAGES (text strings) or LC_CTYPE (character sets) and LC_TIME (time conventions) too at most. You may find that if you set LC_NUMERIC or some other categories, you will start outputting decimal numbers with strange thousand separators and decimal points and they will be unparseable in other countries.

The second parameter is the locale name. If it is an empty string, then this information will be fetched from environment variables.

Note that setlocale() will cause every part of your program to start operating in the new, non-default (C) locale, including C library functions. So don't be surprised if POSIX::ctime returns "Montag, 22. Juli 1996, 12:08:25 Uhr EDT" instead of "Mon Jul 22 12:08:25 EDT 1996", if you set LC_TIME or LC_ALL using setlocale().

setlocale(LC_MESSAGES, "");

Decide on a unique identifier that will distinguish your program's text strings in the LC_MESSAGES database. This would usually be the name of your program.

By default, locale information is found in OS dependant system directories such as /usr/share/locale, or any directory found in the $PATH-like environment variable $NLSPATH. I recommend that you do not install files in /usr. If your program is installed in a directory tree such as /opt/my_package_name/{bin,man,lib,etc}, then you could use /opt/my_package_name/locale to store locale information specific to your program, or you could put in somewhere in /usr/local/share/locale.

Wherever you put it, if it is not one of the default directories, you will need to call bindtextdomain() to tell the library where to find your files. The first parameter is your database's identifier that you chose above.

# oo interface:
my $d = Locale::gettext->domain("my_domain");
$d->dir("/opt/my_package_name/locale");

# traditional interface:
bindtextdomain("my_domain", "/opt/my_package_name/locale");
textdomain("my_domain");

That's it for the initializations.

Step 3

Test to see if your program still works after all these mods :-)

Step 4

TRANSLATE!

Read msgfmt(1) for details on this. Basically, for each locale other than the default, you need to create a file like this: Call this file with the .po extension.

domain "my_domain"

msgid  "Welcome to my program"
msgstr "Willkommen in meinem Programm"

msgid  "Help"
msgstr "Hilfe"

The msgid parameter must match exactly the argument to the gettext() function, and msgstr is the corresponding translation.

You can use the xgettext(1) utility to initially construct this file from all of the gettext() calls in your source code. It was designed for C but it works OK with perl.

Step 5

Compile the .po file

$ msgfmt my_file.po

This will create a file called my_domain.mo (default messages.mo) which you should place in the <locale>/LC_MESSAGES/my_domain.mo subdirectory of either a system default directory, a directory in $NLSPATH, or the directory argument to bindtextdomain(). Replace <locale> with the name of the locale for which this file is created.

For example:

$ mkdir -p /opt/my_package/locale/de/LC_MESSAGES
$ mkdir -p /opt/my_package/locale/fr/LC_MESSAGES
$ cd /path/to/my/source/code
$ cd de
$ msgfmt my_domain.po
$ mv my_domain.mo /opt/my_package/locale/de/LC_MESSAGES
$ cd ../fr
$ msgfmt my_domain.po
$ mv my_domain.mo /opt/my_package/locale/fr/LC_MESSAGES

Step 6

Test it out

$ my_program
Welcome to my program
$ LANG=fr my_program
Bienvenue à mon programme
$ LANG=de my_program
Willkommen in meinem Programm

(Or, set only the messages category instead of the whole locale)

$ LC_MESSAGES=fr
$ export LC_MESSAGES
$ my_program
Bienvenue à mon programme