Development:Language API

This is a draft of a document that should define data structures and API to manipulate Moodle lang files.

Motivation

Moodle uses its own mechanism of translated strings and files storage. Other ways of handling localization files are sometimes requested. Some translators want to use gettext library (which is using .po files), some might want to export Moodle strings into custom format (eg. XML) to translate them with an external tool and import them back to Moodle. The Moodle Language API should enable to write additional plugins of strings and help files storage.

This Language API should provide common interface for all future translation tools - it does not change the Moodle core itself. Current get_text() implementation is pretty well tuned, caching is supported and it is hopefully debugged. The work on this API started during the developement of several Moodle language tools - langchecker (searches for no-longer used strings in the English pack), langstats (translation progress monitor) and the new version of admin/lang.php interface.

Language pack URL

The type of API implementation is selected automatically acording to URL scheme. Currently, only "internal" plugin is supported which represents the traditional way of lang packs handling. Such pack should be referenced as

internal://localhost/full/path/to/the/pack

Other language pack repositories might be references as e.g.:

cvs://username:password@cvs.moodle.org/lang/cs_utf8
gettext://localhost/full/path/to/the/pack
xml://localhost/full/path/to/the/pack

API usage examples

Basic usage scenario - get a translated string:

$lang_path = $CFG->dataroot."/lang/".current_language();
$lang_repo = lang_pack_factory("internal://localhost/".$lang_path);
$string = $lang_repo->get_raw_string('identifier', 'module');

Save a customized string translation:

$lang_path = $CFG->dataroot."/lang/".current_language()."_local";
$lang_repo = lang_pack_factory("internal://localhost/".$lang_path);
$lang_repo->save_string('identifier', 'module', $translation);

Commit translation into moodle.org repository:

$lang_repo = lang_pack_factory("cvs://${username}:${password}@cvs.moodle.org/lang/{$langcode}");
$lang_repo->save_module($module, $comment);

Language API implementations

UML diagram of Language API classes

The Language API is defined as interface. Every plugin must implement this interface. The internal plugin (representing traditional way) will be implemented first.

Internal

The internal plugin is defined as

class lang_pack_internal implements lang_pack_api {...}

The internal plugin will use sevaral classes:

lang_pack_internal

This represents the whole pack. It is implemented as a directory - e.g. $CFG->dirroot/lang/en_utf8 or $CFG->dataroot/lang/cs_utf8 etc.

lang_pack_internal_module

represents a single module of a given pack, defines the sub-context of translated texts. It is implemented as a file - e.g. moodle.php or qtype_multichoice.php.

lang_pack_internal_text

represents a single unit of text (word, sentence or whole page) that can be translated and then used in the UI. It is either one $string[] definition or a help file content.

See also

• Development:Places to search for lang strings.