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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. It can be of any page type supported by ikiwiki, except po. It does not have to be named a special way: migration to this plugin does not imply any page 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

Supported languages

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' => 'Français',
                            'es' => 'Castellano',
                            'de' => 'Deutsch',
    }

Decide which pages are translatable

The po_translatable_pages setting configures what pages are translatable. It is a [[ikiwiki/PageSpec]], so you have lots of control over what kind of pages are translatable.

The .po files are not considered as being translatable, so you don't need to worry about excluding them explicitly from this [[ikiwiki/PageSpec]].

Internal links

The po_link_to option in ikiwiki.setup is used to decide how internal links should be generated, depending on web server features and site-specific preferences.

Default linking behavior

If po_link_to is unset, or set to default, ikiwiki's default linking behavior is preserved: \[[destpage]] links to the master language's page.

Link to current language

If po_link_to is set to current, \[[destpage]] links to the destpage's version written in the current page's language, if available, i.e.:

  • foo/destpage/index.LL.html if usedirs is enabled
  • foo/destpage.LL.html if usedirs is disabled

Link to negotiated language

If po_link_to is set to negotiated, \[[page]] links to the negotiated preferred language, i.e. foo/page/.

(In)compatibility notes:

  • if usedirs is disabled, it does not make sense to set po_link_to to negotiated; this option combination is neither implemented nor allowed.
  • if the web server does not support Content Negotiation, setting po_link_to to negotiated will produce a unusable website.

Server support

Apache

Using Apache mod_negotiation makes it really easy to have Apache serve any 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 code) for the wiki context can help to ensure bla/page/index.en.html is served as Content-Language: LL.

lighttpd

lighttpd unfortunately does not support content negotiation.

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

Usage

Templates

The ISTRANSLATION and ISTRANSLATABLE variables can be used to display things only on translatable or translation pages.

Display page's versions in other languages

The OTHERLANGUAGES loop provides ways to display other languages' versions of the same page, and the translations' status.

One typically adds the following code to templates/page.tmpl:

<TMPL_IF NAME="OTHERLANGUAGES">
<div id="otherlanguages">
  <ul>
  <TMPL_LOOP NAME="OTHERLANGUAGES">
    <li>
      <a href="<TMPL_VAR NAME="URL">"><TMPL_VAR NAME="LANGUAGE"></a>
      <TMPL_UNLESS NAME="MASTER">
        (<TMPL_VAR NAME="PERCENT">&nbsp;%)
      </TMPL_UNLESS>
    </li>
  </TMPL_LOOP>
  </ul>
</div>
</TMPL_IF>

The following variables are available inside the loop (for every page in):

  • URL - url to the page
  • CODE - two-letters language code
  • LANGUAGE - language name (as defined in po_slave_languages)
  • MASTER - is true (1) if, and only if the page is a "master" page
  • PERCENT - for "slave" pages, is set to the translation completeness, in percents

Display the current translation status

The PERCENTTRANSLATED variable is set to the translation completeness, expressed in percent, on "slave" pages.

One can use it this way:

<TMPL_IF NAME="ISTRANSLATION">
<div id="percenttranslated">
  <TMPL_VAR NAME="PERCENTTRANSLATED">
</div>
</TMPL_IF>

Additional PageSpec tests

This plugin enhances the regular [[ikiwiki/PageSpec]] syntax with some additional tests that are documented [[here|ikiwiki/pagespec/po]].

Automatic PO file update

Committing changes to a "master" page:

  1. updates the POT file and the PO files for the "slave" languages; the updated PO files are then put under version control;
  2. triggers a refresh of the corresponding HTML slave pages.

Also, when the plugin has just been enabled, or when a page has just been declared as being translatable, the needed POT and PO files are created, and the PO files are checked into version control.

Discussion pages

Discussion should happen in the language in which the pages are written for real, i.e. the "master" one. If discussion pages are enabled, "slave" pages therefore link to the "master" page's discussion page.

Translating

One can edit the PO files using ikiwiki's CGI (a message-by-message interface could also be implemented at some point).

If [[tips/untrusted_git_push]] is setup, one can edit the PO files in one's preferred $EDITOR, without needing to be online.

TODO

Security checks

  • Can any sort of directives be put in po files that will cause mischief (ie, include other files, run commands, crash gettext, whatever).
  • Any security issues on running po4a on untrusted content?

gettext/po4a rough corners

  • fix infinite loop when synchronizing two ikiwiki (when checkouts live in different directories): say bla.fr.po has been updated in repo2; pulling repo2 from repo1 seems to trigger a PO update, that changes bla.fr.po in repo1; then pushing repo1 to repo2 triggers a PO update, that changes bla.fr.po in repo2; etc.; fixed in 629968fc89bced6727981c0a1138072631751fee?
  • new translations created in the web interface must get proper charset/encoding gettext metadata, else the next automatic PO update removes any non-ascii chars; possible solution: put such metadata into the Pot file, and let it propagate; should be fixed in 773de05a7a1ee68d2bed173367cf5e716884945a, time will tell.

Misc. improvements

page titles

Use nice page titles from meta plugin in links, as inline already does. This is actually a duplicate for [[bugs/pagetitle_function_does_not_respect_meta_titles]], which might be fixed by something like [[todo/using_meta_titles_for_parentlinks]].

backlinks

po_link_to = negotiated

If a given translatable sourcepage.mdwn links to [[destpage]], sourcepage.LL.po also link to [[destpage]], and the latter has the master page and all its translations listed in the backlinks. On the other hand, translations of destpage get none of these backlinks. What would be nice is:

  • if a translatable page links to another translatable page: the master destpage gets a backlink to the master sourcepage, and every slave destpage gets a backlink to the corresponding slave sourcepage
  • if a translatable page links to a non-translatable page: the destpage gets a backlink to the master sourcepage only
  • if a non-translatable page links to a translatable page: every master or slave destpage gets a backlink to the sourcepage
  • if a non-translatable page links to another non-translatable page: the default behavious is nice, don't change it

po_link_to = current

At first glance, backlinks seem to work nicely, but a more thorough look is needed.

po_link_to = default

FIXME

Translation quality assurance

Modifying a PO file via the CGI must be forbidden if the new version is not 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.