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[[!template id=plugin name=po core=0 author="[[intrigeri]]"]] [[!tag type/format]]

This plugin adds support for multi-lingual wikis, translated with gettext, using po4a.

It depends on the Perl Locale::Po4a::Po library (apt-get install po4a).

Introduction

A language is chosen as the "master" one, and any other supported language is a "slave" one.

A page written in the "master" language is a "master" page, and is written in any supported format but PO. It does not have to be named a special way: migration from/to this plugin does not imply heavy renaming work.

Example: bla/page.mdwn is a "master" Markdown page written in English; if usedirs is enabled, it is rendered as bla/page/index.en.html, else as bla/page.en.html.

Any translation of a "master" page into a "slave" language is called a "slave" page; it is written in the gettext PO format. PO is now a page type supported by ikiwiki.

Example: bla/page.fr.po is the PO "message catalog" used to translate bla/page.mdwn into French; if usedirs is enabled, it is rendered as bla/page/index.fr.html, else as bla/page.fr.html

Configuration

po_master_language is used to set the master language in ikiwiki.setup, such as:

    po_master_language => { 'code' => 'en', 'name' => 'English' }

po_slave_languages is used to set the list of supported "slave" languages, such as:

    po_slave_languages => { 'fr' => { 'name' => 'Français', },
                            'es' => { 'name' => 'Castellano', },
                            'de' => { 'name' => 'Deutsch', }
    }

Server support

Apache

Using mod_negotiation makes it really easy to have Apache serve the page in the client's preferred language, if available. This is the default Debian Apache configuration.

When usedirs is enabled, one has to set DirectoryIndex index for the wiki context.

Setting DefaultLanguage LL (replace LL with your default MIME language) for the wiki context can be needed, to ensure bla/page/index.en.html is served as Content-Language: LL. FIXME: is it still needed with the new .en.html naming convention?

lighttpd

lighttpd unfortunately does not support content negotiation.

FIXME: does mod_magnet provide the functionality needed to emulate this?

TODO

Links

Choice between two behaviors must be possible in ikiwiki.setup; a po_link_to_current_language option must allow switching between them.

If po_link_to_current_language is disabled, [[page]] links to the negotiated preferred language, i.e.:

  • usedirs enabled: bla/page/
  • usedirs disabled: bla/page

This obviously does not work in case Content Negotiation is not supported by the web server, hence one can enable po_link_to_current_language to make [[page]] link to the current page's language, i.e.:

  • usedirs enabled: bla/page/index.LL.html
  • usedirs disabled: bla/page.LL.html

FIXME: should po_link_to_current_language be enabled by default?

Display available translations

The [[linguas|plugins/contrib/linguas]] plugin has some code that can be used as a basis to display the existing translations, and allow to navigate between them.

View translation status

One should be able to view some information about the translation completeness, either for a given page or for the whole wiki.

This should not be too hard using gettext tools. If this is implemented as a [[HTML::Template|http://search.cpan.org/search?mode=dist&query=HTML%3A%3ATemplate]] loop, a page using it should depend on any "master" and "slave" pages whose status is being displayed.

Decide which pages are translatable

The subset of "master" pages subject to translation must be configurable:

  • a [[!translatable ]] directive, when put on a page, makes it translatable
  • to set at once a bunch of pages as being translatable, use this [[ikiwiki/directive]] with the match=PageSpec argument.

Automatic PO files update

Committing changes to a "master" page must:

  1. update the POT file and the PO files for the supported languages, before putting them under version control
  2. trigger a refresh of the corresponding HTML slave pages

The former is to be done at a time when:

  • we know which "master" page was modified, and thus, which POT/PO files have to be updated: the needsbuild hook is the first one to run that provides us with the necessary information
  • we can modify the list of pages needing a refresh; this is needsbuild hook's job

The latter can be implemented by making any "slave" page depend on the corresponding "master" page. The add_depends function can achieve this, if used in a FIXME hook.

UI consistency: rename "Edit" button on slave pages

It may be surprising to some, after having pressed Edit on a wiki page, to end up editing a strange looking PO file. The Edit button displayed on "slave" pages must therefore be renamed Improve translation .

Pages selection depending on language

To improve user navigation in a multi-lingual wiki, site developers must be enabled to write:

    \[[!map pages="dev/* and lang(LL)" feeds="no"]]

    \[[!map pages="dev/* and currentlang()" feeds="no"]]

Translation quality assurance

Modifying a PO file via the CGI must only be allowed if the new version is a valid PO file. As a bonus, check that it provides a more complete translation than the existing one.

A new cansave type of hook would be needed to implement this.

Note: committing to the underlying repository is a way to bypass this check.

Translating online

As PO is a wiki page type, we already have an online PO editor, that is ikiwiki's CGI.

A message-by-message interface could also be implemented at some point; a nice way to do offline translation work (without VCS access) still has to be offered, though.

Translating offline without VCS access

The following workflow should be made possible for translators without VCS access who need to edit the PO files in another editor than a web browser:

  • download the page's PO file
  • use any PO editor to update the translation
  • upload the updated PO file

Implementation note: a generic mechanism to upload a page's source is needed: it's only an alternative way to allow saving a the modified page's source with the CGI.

Short-term workflow

A possible workaround is:

  • pretend to edit the PO file online
  • copy the PO file content from the textarea
  • cancel the edit
  • paste the content into a local file.
  • edit the local file in any PO editor
  • pretend to edit the PO file online
  • paste the modified local file's content into the edit textarea
  • save