Issue #2216541 by jhodgdon, Gábor Hojtsy: Fill in topic/@defgroup docs for...

Issue #2216541 by jhodgdon, Gábor Hojtsy: Fill in topic/@defgroup docs for Internationalization overview.

core/lib/Drupal/Core/Annotation/Translation.php

@@ -36,6 +36,8 @@
  * @endcode
  * Other t() arguments like language code are not valid to pass in. Only
  * context is supported.
+ *
+ * @see i18n
  * @}
  */
 
@@ -47,9 +49,9 @@
  * specified, a context for that string. The string (with optional context)
  * is passed into t().
  *
- * @Annotation
- *
  * @ingroup plugin_translatable
+ *
+ * @Annotation
  */
 class Translation extends AnnotationBase {
 

core/lib/Drupal/Core/Datetime/Date.php

@@ -18,6 +18,8 @@
 
 /**
  * Provides a service to handler various date related functionality.
+ *
+ * @ingroup i18n
  */
 class Date {
   use StringTranslationTrait;

core/lib/Drupal/Core/StringTranslation/StringTranslationTrait.php

@@ -18,6 +18,8 @@
  * Procedural code must use the global function t(). Any other approach will
  * result in untranslatable strings, because the string extractor will not be
  * able to find them.
+ *
+ * @ingroup i18n
  */
 trait StringTranslationTrait {
 

core/lib/Drupal/Core/StringTranslation/TranslationInterface.php

@@ -7,6 +7,11 @@
 
 namespace Drupal\Core\StringTranslation;
 
+/**
+ * Interface for the translation.manager translation service.
+ *
+ * @ingroup i18n
+ */
 interface TranslationInterface {
 
   /**

core/modules/locale/locale.api.php

@@ -8,7 +8,6 @@
 /**
  * @defgroup interface_translation_properties Interface translation properties
  * @{
- *
  * .info.yml file properties for interface translation settings.
  *
  * For modules hosted on drupal.org, a project definition is automatically added
@@ -78,7 +77,8 @@
  * - "%version": Project version release. Value examples: "8.1", "8.x-1.0".
  * - "%language": Language code. Value examples: "fr", "pt-pt".
  *
- * @} End of "defgroup interface_translation_properties".
+ * @see i18n
+ * @}
  */
 
 /**
@@ -110,6 +110,7 @@
  *   Project data as returned by update_get_projects().
  *
  * @see locale_translation_project_list().
+ * @ingroup interface_translation_properties
  */
 function hook_locale_translation_projects_alter(&$projects) {
   // The translations are located at a custom translation sever.

core/modules/system/core.api.php

@@ -188,7 +188,8 @@
  * structure of the configuration, its data types, and which of its values need
  * to be translatable. Each module needs to define its configuration schema in
  * files in the config/schema directory under the top-level module directory, so
- * look there in most Core modules for examples.
+ * look there in most Core modules for examples. Note that data types label,
+ * text, and data_format are translatable; string is non-translatable text.
  *
  * @section sec_simple Simple configuration
  * The simple configuration API should be used for information that will always
@@ -261,6 +262,9 @@
  *   overriding the
  *   \Drupal\Core\Config\Entity\ConfigEntityInterface::calculateDependencies()
  *   method.
+ *
+ * @see i18n
+ *
  * @}
  */
 
@@ -413,6 +417,8 @@
  *   ->execute();
  * $files = $storage->loadMultiple($fids);
  * @endcode
+ *
+ * @see i18n
  * @}
  */
 
@@ -456,12 +462,77 @@
  * @{
  * Internationalization and translation
  *
- * @todo write this
- *
- * Additional documentation paragraphs need to be written, and functions,
- * classes, and interfaces need to be added to this topic.
+ * The principle of internationalization is that it should be possible to make a
+ * Drupal site in any language (or a multi-lingual site), where only content in
+ * the desired language is displayed for any particular page request. In order
+ * to make this happen, developers of modules, themes, and installation profiles
+ * need to make sure that all of the displayable content and user interface (UI)
+ * text that their project deals with is internationalized properly, so that it
+ * can be translated using the standard Drupal translation mechanisms.
+ *
+ * @section internationalization Internationalization
+ * Different @link info_types types of information in Drupal @endlink have
+ * different methods for internationalization, and different portions of the
+ * UI also have different methods for internationalization. Here is a list of
+ * the different mechanisms for internationalization, and some notes:
+ * - UI text is always put into code and related files in English.
+ * - Any time UI text is displayed using PHP code, it should be passed through
+ *   either the global t() function or a t() method on the class. If it
+ *   involves plurals, it should be passed through either the global
+ *   formatPlural() function or a formatPlural() method on the class. Use
+ *   \Drupal\Core\StringTranslation\StringTranslationTrait to get these methods
+ *   into a class.
+ * - Dates displayed in the UI should be passed through the 'date' service
+ *   class's format() method. Again see the Services topic; the method to
+ *   call is \Drupal\Core\Datetime\Date::format().
+ * - Some YML files contain UI text that is automatically translatable:
+ *   - *.routing.yml files: route titles. This also applies to
+ *     *.local_tasks.yml, *.local_actions, and *.contextual_links.yml files.
+ *   - *.info.yml files: module names and descriptions.
+ * - For configuration, make sure any configuration that is displayable to
+ *   users is marked as translatable in the configuration schema. Configuration
+ *   types label, text, and date_format are translatable; string is
+ *   non-translatable text. See the @link config_api Config API topic @endlink
+ *   for more information.
+ * - For annotation, make sure that any text that is displayable in the UI
+ *   is wrapped in \@Translation(). See the
+ *   @link plugin_translatable Plugin translatables topic @endlink for more
+ *   information.
+ * - Content entities are translatable if they have
+ *   @code
+ *   translatable = TRUE,
+ *   @endcode
+ *   in their annotation. The use of entities to store user-editable content to
+ *   be displayed in the site is highly recommended over creating your own
+ *   method for storing, retrieving, displaying, and internationalizing content.
+ * - For Twig templates, use 't' or 'trans' filters to indicate translatable
+ *   text. See https://www.drupal.org/node/2133321 for more information.
+ * - In JavaScript code, use the Drupal.t() and Drupal.formatPlural() functions
+ *   (defined in core/misc/drupal.js) to translate UI text.
+ * - If you are using a custom module, theme, etc. that is not hosted on
+ *   Drupal.org, see
+ *   @link interface_translation_properties Interface translation properties topic @endlink
+ *   for information on how to make sure your UI text is translatable.
+ *
+ * @section translation Translation
+ * Once your data and user interface are internationalized, the following Core
+ * modules are used to translate it into different languages (machine names of
+ * modules in parentheses):
+ * - Language (language): Define which languages are active on the site.
+ * - Interface Translation (locale): Translate UI text.
+ * - Content Translation (content_translation): Translate content entities.
+ * - Configuration Translation (config_translation): Translate configuration.
+ *
+ * The Interface Translation module deserves special mention, because besides
+ * providing a UI for translating UI text, it also imports community
+ * translations from the
+ * @link https://localize.drupal.org Drupal translation server. @endlink If
+ * UI text in Drupal Core and contributed modules, themes, and installation
+ * profiles is properly internationalized (as described above), the text is
+ * automatically added to the translation server for community members to
+ * translate.
  *
- * See https://drupal.org/node/2133321 and https://drupal.org/node/303984
+ * @see transliteration
  * @}
  */