phpmaster | Localizing PHP Applications Part 3: Nov 2011 - Sitepoint

This article delves into advanced techniques for using the gettext library in PHP, focusing on fallback locales, locale switching, and overriding message domains.

Key Concepts:

• Default Locale: Establish your application's default language early in development. Using the default locale's strings as msgids in other domains streamlines translation and improves performance. Avoid translating the default language to itself.
• Locale Switching: Easily switch locales by instructing gettext to use a different domain. This is typically handled at the application's start or within an included file.
• Domain Overriding: Use dgettext() to switch between multiple translation domains. Remember that gettext() uses only one default domain, set via textdomain(), while dgettext() requires domains to be pre-bound using bindtextdomain().
• PHP Localization Benefits: PHP localization is vital for global reach, enhancing user experience and market accessibility.

Directory Structure and Fallback Locales:

An optimal directory structure avoids unnecessary translation of the default locale (e.g., en_US). Instead of using identifiers like "HELLO_WORLD", use the actual default language string directly as the msgid. This approach minimizes processing overhead.

The image below illustrates a sample directory structure:

Example translation files (.po and compiled .mo):

French (fr_FR):

<code>#Test token 1
msgid "Hello World!"
msgstr "Bonjour tout le monde!"

#Test token 2
msgid "Testing Translation..."
msgstr "Test de traduction..."</code>

Spanish (es_ES):

<code>#Test token 1
msgid "Hello World!"
msgstr "¡Hola mundo!"

#Test token 2
msgid "Testing Translation..."
msgstr "Prueba de traducción..."</code>

Arabic (ar_EG):

<code>#Test token 1
msgid "Hello World!"
msgstr "!أهلا بالعالم"

#Test token 2
msgid "Testing Translation..."
msgstr "...اختبار الترجمة"</code>

Switching Locales:

The locale.php file manages locale selection using GET parameters or sessions:

<?php session_start();

$language = isset($_GET["lang"]) ? $_GET["lang"] : (isset($_SESSION["lang"]) ? $_SESSION["lang"] : "en_US");
$_SESSION["Language"] = $language;

$folder = "Locale";
$domain = "messages";
$encoding = "UTF-8";

putenv("LANG=" . $language);
setlocale(LC_ALL, $language);

bindtextdomain($domain, $folder);
bind_textdomain_codeset($domain, $encoding);

textdomain($domain);
?>

A sample usage in test-locale.php:

<?php require_once "locale.php";

echo _("Hello World!"), "<br>";
echo _("Testing Translation...");
?>

Accessing test-locale.php?lang=fr_FR will output the French translation.

Overriding the Current Domain:

Use dgettext() to access translations from a different domain (e.g., "errors"). Crucially, remember to bind this domain using bindtextdomain() in locale.php:

<?php // ... (locale.php code) ...
bindtextdomain("errors", "Locale");
bind_textdomain_codeset("errors", "UTF-8");
// ... (rest of locale.php code) ...
?>

In test-locale.php:

<?php // ... (include locale.php) ...
echo "<br>";
echo dgettext("errors", "Error getting content"), "<br>";
echo dgettext("errors", "Error saving data");
?>

This will correctly translate "Error getting content" and "Error saving data" if translations exist in the "errors" domain for the selected locale.

Summary and FAQ:

This section summarizes the key learnings and provides answers to frequently asked questions about PHP localization, covering topics such as best practices, handling plurals, right-to-left languages, and managing translations. The FAQ section is extensive and provides in-depth information on various aspects of PHP localization. The original FAQ section has been retained in its entirety.

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