1. Internationalization for
Plugin and Theme Developers
Sergey Biryukov
WordCamp Milano 2016

2. Sergey Biryukov
● WordPress Core Contributor at Yoast
yoast.com
● Co-founder of Russian WP community
ru.wordpress.org
● Polyglots, Support, and Meta teams
sergeybiryukov.com
@SergeyBiryukov

3. Plugins and Themes for the Whole World
● Internationalization (i18n) — providing the ability to translate
● Localization (L10n) — translating to a particular language

4. Plugins and Themes for the Whole World
● Over 100 languages
● More robust code
● Feedback
● It’s easy

5. Localized Theme Directories

6. Localized Plugin Directories

7. Introduction to gettext
● Text domain
– 'my-plugin'
● Preparing the strings
– <?php echo 'Title'; ?>→<?php _e( 'Title', 'my-plugin' ); ?>
● Language files
– .pot, .po, .mo

8. Text Domain
● Should match the plugin/theme slug (folder name):
– wp-content/plugins/my-plugin→'my-plugin'
– wp-content/themes/my-theme→'my-theme'
● Should be added to plugin/theme headers:
– Plugin Name: My Plugin
– Version: 1.0
– Text Domain: my-plugin

9. Text Domain
● Loading the text domain
– load_plugin_textdomain( 'my-plugin', false,
dirname( plugin_basename( __FILE__ ) ) . '/languages' );
– load_theme_textdomain( 'my-theme',
get_template_directory() . '/languages' );

10. Text Domain
● Loading the text domain
– load_plugin_textdomain( 'my-plugin', false,
dirname( plugin_basename( __FILE__ ) ) . '/languages' );
– load_theme_textdomain( 'my-theme',
get_template_directory() . '/languages' );
● wp-content/languages (WordPress 4.6+)

11. Preparing the Strings
● Regular strings:
– __( 'Hello world!', 'my-plugin' );
– _e( 'Hello world!', 'my-plugin' );
● Strings with context:
– _x( 'Hello world!', 'post title', 'my-plugin' );
– _ex( 'Hello world!', 'post title', 'my-plugin' );

12. Preparing the Strings
● Plural forms:
– _n( '%d item', '%d items', $count, 'my-plugin' );
– _nx( '%d item', '%d items', $count, 'comments', 'my-plugin' );
● If the number is not available yet:
– _n_noop( '%d item', '%d items', 'my-plugin' );
– _nx_noop('%d item', '%d items', 'comments', 'my-plugin' );

13. Preparing the Strings
● Escaping HTML tags:
– esc_html__( 'Hello <em>world</em>!', 'my-plugin' );
– esc_html_e( 'Hello <em>world</em>!', 'my-plugin' );
– esc_html_x( 'Hello <em>world</em>!', 'post title', 'my-plugin' );
● Escaping HTML attributes:
– esc_attr__( 'Hello "world"!', 'my-plugin' );
– esc_attr_e( 'Hello "world"!', 'my-plugin' );
– esc_attr_x( 'Hello "world"!', 'post title', 'my-plugin' );

14. Preparing the Strings
● Escaping HTML tags and attributes:
– <option value="<?php esc_attr_e( 'value', 'my-plugin' ); ?>">
<?php esc_html_e( 'Option label', 'my-plugin' ); ?>
</option>
● Same, in a longer notation:
– <option value="<?php echo esc_attr( __( 'value', 'my-plugin' ) ); ?>">
<?php echo esc_html( __( 'Option label', 'my-plugin' ) ); ?>
</option>

15. _e() ≠ echo()
● Don’t use PHP variables, only simple strings:
– _e( $string ); — don’t do that.
● Provide the ability to translate whole phrases, not separate words:
– echo __( 'Hello' ) . ' ' . __( 'world!' ); — don’t do that either.
● Don’t forget the text domain:
– _e( 'Hello world!', 'my-plugin' );
● Remove unnecessary HTML markup from the strings:
– _e( '<p>Hello world!</p>', 'my-plugin' );

16. Context and Comments
● Context — same string, different translations:
– _x( 'redirect', 'noun', 'my-plugin' );
– _x( 'redirect', 'verb', 'my-plugin' );
● Comments — to explain placeholders in a string:
– /* translators: %s: file name */
__( '%s was deleted.', 'my-plugin' );

17. Plural Forms
● ???
– _e( "You have $count items.", 'my-plugin' );
– _e( 'You have ' . $count . ' items.', 'my-plugin' );
– printf( __( 'You have %d items.', 'my-plugin' ), $count );
– printf( _n( 'You have %d item.', 'You have %d items.', $count ),
$count );

18. Plural Forms
● Incorrect:
– _e( "You have $count items.", 'my-plugin' );
– _e( 'You have ' . $count . ' items.', 'my-plugin' );
– printf( __( 'You have %d items.', 'my-plugin' ), $count );
● Almost correct:
– printf( _n( 'You have %d item.', 'You have %d items.', $count ),
$count );

19. Plural Forms
● Correct:
– printf( _n( 'You have %d item.', 'You have %d items.', $count ),
number_format_i18n( $count ) );
● number_format_i18n() — for displaying numbers
● date_i18n() — for displaying dates

20. Plural Forms
● If the number is not available:
– $items_plural = _n_noop( 'You have %s item.', 'You have %s items',
'my-plugin' );
● ...
● After it’s available:
– printf( translate_nooped_plural( $items_plural, $count ),
number_format_i18n( $count ) );
● translate_nooped_plural() — for deferred translations of plural strings

21. Plural Forms
● The first form is not necessarily used for 1 item:
– printf( _n( 'Theme deleted.', '%d themes deleted.', $count ),
number_format_i18n( $count ) );
● Better:
– if ( 1 === $count ) {
_e( 'Theme deleted.' );
– } else {
printf( _n( '%d theme deleted.', '%d themes deleted.', $count ),
number_format_i18n( $count ) );
– }

22. Language Files
● .pot (Portable Object Template)
– Translation template, contains English strings only.
● .po (Portable Object)
– Language file in a human-readable format.
● .mo (Machine Object)
– Compiled language file in a machine-readable format.

23. Language Files
makepot.php→.pot→Poedit→.po/.mo→email

24. Plugin Changelog
● Version 1.5.6
– Added Russian translation.
– That’s it!
● Version 1.5.6.1
– Fixed a typo in Russian translation.

25. Language Files
makepot.php→.pot→Poedit→.po/.mo→email
translate.wordpress.org

26. translate.wordpress.org

27. translate.wordpress.org
● GTE (General Translation Editor) — locale editors
– Can check and approve all translations.
● PTE (Project Translation Editor) — project editors
– Can approve translations for a particular project.
● Translators
– Can suggest translations.

28. If Someone Has Sent You Their Translation
● Ask them to create a WordPress.org account
– They can be added as a Project Translation Editor.
– They would be able to import the .po file themselves.
– ...and continue translating in the future.
● Ask locale editors to import the files
– No guarantee that the plugin will continue to be actively translated.

29. If Someone Has Sent You Their Translation
● Once the translator has a WordPress.org account:
– Go to the Polyglots team blog:
https://make.wordpress.org/polyglots/
– Find the Polyglots Handbook link:
https://make.wordpress.org/polyglots/handbook/
– On “Theme & Plugin Directories” page, find a post template for
requesting new translation editors.
– Submit your request to the Polyglots blog and wait for a reply.

30. @SergeyBiryukov
Thanks! Questions?