Provided by: libdist-zilla-localetextdomain-perl_0.90-2_all 
Name
Dist::Zilla::LocaleTextDomain - Tools for managing Locale::TextDomain language catalogs
Synopsis
In dist.ini:
[ShareDir]
[LocaleTextDomain]
textdomain = My-App
share_dir = share
Scan localizable messages from your Perl libraries into a language template file,
po/My-App.pot:
dzil msg-scan
Initialize language translation files:
dzil msg-init fr de.UTF-8
Merge changes to localizable messages into existing translation files:
dzil msg-merge
Compile translation files into message catalogs for testing:
dzil msg-compile --dest-dir . fr de.UTF-8
Binary message catalogs are automatically added to your distribution by the "build" and
"release" commands:
dzil build
dzil release
Description
Locale::TextDomain provides a nice interface for localizing your Perl applications. The
tools for managing translations, however, is a bit arcane. Fortunately, you can just use
this plugin and get all the tools you need to scan your Perl libraries for localizable
strings, create a language template, and initialize translation files and keep them up-to-
date. All this is assuming that your system has the gettext
<http://www.gnu.org/software/gettext/> utilities installed.
The Details
I put off learning how to use Locale::TextDomain for quite a while because, while the
gettext <http://www.gnu.org/software/gettext/> tools are great for translators, the tools
for developers were a little more opaque, especially for Perlers used to Locale::Maketext.
But I put in the effort while hacking Sqitch. As I had hoped, using it in my code was
easy. Using it for my distribution was harder, so I decided to write
Dist::Zilla::LocaleTextDomain to make life simpler for developers who manage their
distributions with Dist::Zilla.
What follows is a quick tutorial on using Locale::TextDomain and managing its translation
files with Dist::Zilla::LocaleTextDomain.
This is my domain
First thing to do is to start using Locale::TextDomain in your code. Load it into each
module with the name of your distribution, as set by the "name" attribute in your dist.ini
file. For example, if your dist.ini looks something like this:
name = My-GreatApp
author = Homer Simpson <homer@example.com>
license = Perl_5
Then, in you Perl libraries, load Locale::TextDomain like this:
use Locale::TextDomain qw(My-GreatApp);
use Locale::Messages qw(bind_textdomain_filter);
use Encode;
$ENV{OUTPUT_CHARSET} = 'UTF-8';
bind_textdomain_filter 'My-GreatApp' => \&Encode::decode_utf8;
Locale::TextDomain uses the string we pass to it to find localization catalogs, so
naturally Dist::Zilla::LocaleTextDomain will use it to put those catalogs in the right
place. It's also a best practice to coerce Locale::TextDomain to return character strings,
rather than bytes, by setting the $OUTPUT_CHARSET environment variable to "UTF-8" and then
binding a filter to decode the resulting strings into Perl character strings. This makes
it easier to work with such strings in our application. Just be sure to encode them before
outputting them!
Okay, so it's loaded, how do you use it? The documentation for the Locale::TextDomain
exported functions is quite comprehensive, and I think you'll find it pretty simple once
you get used to it. For example, simple strings are denoted with "__":
say __ 'Hello';
If you need to specify variables, use "__x":
say __x(
'You selected the color {color}',
color => $color
);
Need to deal with plurals? Use "__n"
say __n(
'One file has been deleted',
'All files have been deleted',
$num_files,
);
And then you can mix variables with plurals with "__nx":
say __nx(
'One file has been deleted.',
'{count} files have been deleted.',
$num_files,
count => $num_files,
);
Pretty simple, right? Get to know these functions, and just make it a habit to use them in
user-visible messages in your code. Even if you never expect to translate those messages,
just by doing this you make it easier for someone else to come along and start translating
for you.
The setup
Now you've internationalized your code. Great! What's next? Officially, nothing. If you
never do anything else, your code will always emit the messages as written. You can ship
it and things will work just as if you had never done any localization.
But what's the fun in that? Let's set things up so that translation catalogs will be built
and distributed once they're written. Add these lines to your dist.ini:
[ShareDir]
[LocaleTextDomain]
There are actually quite a few attributes you can set here to tell the plugin where to
find language files and where to put them. For example, if you used a domain different
from your distribution name, e.g.,
use Locale::TextDomain 'com.example.My-GreatApp';
Then you would need to set the "textdomain" attribute so that the "LocaleTextDomain"
plugin does the right thing with the language files:
[LocaleTextDomain]
textdomain = com.example.My-GreatApp
Consult the "LocaleTextDomain" configuration docs for details on all available attributes.
(Prior to Locale::TextDomain v1.21, there was no "ShareDir" support. If you're unfortunate
to be stuck with one of these earlier versions, you'll need to set the "share_dir"
attribute to "lib" instead of the default value, "share". If you use Module::Build, you'll
also need a subclass to do the right thing with the catalog files; see "Installation" in
Dist::Zilla::Plugin::LocaleTextDomain for details.)
What does including the plugin do? Mostly nothing. You might see this line from "dzil
build", though:
[LocaleTextDomain] Skipping language compilation: directory po does not exist
Now at least you know it was looking for something to compile for distribution. Let's give
it something to find.
Initialize languages
To add translation files, use the "msg-init" command:
> dzil msg-init de
Created po/de.po.
At this point, the gettext <http://www.gnu.org/software/gettext/> utilities will need to
be installed and visible in your path, or else you'll get errors.
This command scans all of the Perl modules gathered by Dist::Zilla and initializes a
German translation file, named po/de.po. This file is now ready for your German-speaking
public to start translating. Check it into your source code repository so they can find
it. Create as many language files as you like:
> dzil msg-init fr ja.JIS en_US.UTF-8
Created po/fr.po.
Created po/ja.po.
Created po/en_US.po.
As you can see, each language results in the generation of the appropriate file in the po
directory, sans encoding (i.e., no .UTF-8 in the "en_US" file name).
Now let your translators go wild with all the languages they speak, as well as the
regional dialects. (Don't forget to colour your code with "en_UK" translations!)
Once you have translations and they're committed to your repository, when you build your
distribution, the language files will automatically be compiled into binary catalogs.
You'll see this line output from "dzil build":
[LocaleTextDomain] Compiling language files in po
po/fr.po: 10 translated messages, 1 fuzzy translation, 0 untranslated messages.
po/ja.po: 10 translated messages, 1 fuzzy translation, 0 untranslated messages.
po/en_US.po: 10 translated messages, 1 fuzzy translation, 0 untranslated messages.
You'll then find the catalogs in the shared directory of your distribution:
> find My-GreatApp-0.01/share -type f
My-GreatApp-0.01/share/LocaleData/de/LC_MESSAGES/My-GreatApp.mo
My-GreatApp-0.01/share/LocaleData/en_US/LC_MESSAGES/My-GreatApp.mo
My-GreatApp-0.01/share/LocaleData/ja/LC_MESSAGES/My-GreatApp.mo
These binary catalogs will be installed as part of the distribution just where
"Locale::TextDomain" can find them.
Here's an optional tweak: add this line to your "MANIFEST.SKIP":
^po/
This prevents the po directory and its contents from being included in the distribution.
Sure, you can include them if you like, but they're not required for the running of your
app; the generated binary catalog files are all you need. Might as well leave out the
translation files.
But I'm a Translator
Not a developer, but want to translate a project? I've written this special section just
for you.
Translating your language is relatively straight-forward. First, make sure that the
translation file is up-to-date. Say you're translating into French; use the "msg-merge"
command to update the translation file:
> dzil msg-merge po/fr.po
[LocaleTextDomain] Merging gettext strings into po/fr.po
If you get an error about it not existing, use the "msg-init" command to create it:
> dzil msg-init fr
[LocaleTextDomain] Created po/fr.po.
Now edit po/fr.po. You can use a tool such as Poedit <http://www.poedit.net> or Emacs
<https://www.gnu.org/software/gettext/manual/html_node/PO-Mode.html> to make it easier. As
you work, you can use the "msg-compile" command to make sure that you're translation file
is error-free:
> dzil msg-compile po/fr.po
[LocaleTextDomain] po/fr.po: 195 translated messages.
This command compiles a catalog file into the LocaleData subdirectory of the current
directory (or directory of your choice via the "--dest-dir" option), so that you can even
run the app with the compiled catalog to make sure things look the way you think they
ought to. Just set the $LANGUAGE environment variable and make sure that Perl includes the
current directory in its path, something like:
LANGUAGE=fr perl -I . bin/myapp.pl
Consult the developer for help with this bit, as how apps run varies between projects.
Mergers and acquisitions
You've got translation files and helpful translators given them a workover. What happens
when you change your code, add new messages, or modify existing ones? The translation
files need to periodically be updated with those changes, so that your translators can
deal with them. We got you covered with the "msg-merge" command:
> dzil msg-merge
extracting gettext strings
Merging gettext strings into po/de.po
Merging gettext strings into po/en_US.po
Merging gettext strings into po/ja.po
This will scan your module files again and update all of the translation files with any
changes. Old messages will be commented-out and new ones added. Just commit the changes to
your repository and notify the translation army that they've got more work to do.
If for some reason you need to update only a subset of language files, you can simply list
them on the command-line:
> dzil msg-merge po/de.po po/en_US.po
Merging gettext strings into po/de.po
Merging gettext strings into po/en_US.po
What's the scan, man
Both the "msg-init" and "msg-merge" commands depend on a translation template file to
create and merge language files. Thus far, this has been invisible: they will create a
temporary template file to do their work, and then delete it when they're done.
However, it's common to also store the template file in your repository and to manage it
directly, rather than implicitly. If you'd like to do this, the "msg-scan" command will
scan the Perl module files gathered by Dist::Zilla and make it for you:
> dzil msg-scan
extracting gettext strings into po/My-GreatApp.pot
The resulting .pot file will then be used by "msg-init" and "msg-merge" rather than
scanning your code all over again. This actually then makes "msg-merge" a two-step
process: You need to update the template before merging. Updating the template is done by
exactly the same command, "msg-scan":
> dzil msg-scan
extracting gettext strings into po/My-GreatApp.pot
> dzil msg-merge
Merging gettext strings into po/de.po
Merging gettext strings into po/en_US.po
Merging gettext strings into po/ja.po
Ship It!
And that's all there is to it. Go forth and localize and internationalize your Perl apps!
Author
David E. Wheeler <david@justatheory.com>
Copyright and License
This software is copyright (c) 2012-2013 by David E. Wheeler.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.