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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).


[[!toc levels=2]]


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


(In)Compatibility


This plugin does not support the indexpages mode. If you don't know
what it is, you probably don't care.


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


When po_link_to is not set to negotiated, one should replace some
occurrences of BASEURL with HOMEPAGEURL to get correct links to
the wiki homepage.


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. 

  2. triggers a refresh of the corresponding HTML slave pages.
    3. 



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 and other sub-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.


Likewise, "slave" pages are not supposed to have sub-pages;
[[WikiLinks|wikilink]] that appear on a "slave" page therefore link to
the master page's sub-pages.


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.


Markup languages support


Markdown is well supported. Some other markup languages supported by
ikiwiki mostly work, but some pieces of syntax are not rendered
correctly on the slave pages:


    

  • [[reStructuredText|rst]]: anonymous hyperlinks and internal
cross-references
    • 

  • [[wikitext]]: conversion of newlines to paragraphs
    • 

  • [[creole]]: verbatim text is wrapped, tables are broken
    • 

  • [[html]] and LaTeX: not supported yet; the dedicated po4a modules
could be used to support them, but they would need a security audit
    • 

  • other markup languages have not been tested.
    • 



Security


[[./security]] contains a detailed security analysis of this plugin
and its dependencies.


When using po4a older than 0.35, it is recommended to uninstall
Text::WrapI18N (Debian package libtext-wrapi18n-perl), in order to
avoid a potential denial of service.


TODO


Better links


Page title in links


Using the fix to
[[bugs/pagetitle_function_does_not_respect_meta_titles]] from
[[intrigeri]]'s meta branch, the generated links' text is based on
the page titles set with the [[meta|plugins/meta]] plugin. This has to
be merged into ikiwiki upstream, though.


Robustness tests


Enabling/disabling the plugin


    

  • enabling the plugin with po_translatable_pages set to blacklist: OK
    • 

  • enabling the plugin with po_translatable_pages set to whitelist: OK
    • 

  • enabling the plugin without po_translatable_pages set: OK
    • 

  • disabling the plugin: OK
    • 



Changing the plugin config


    

  • adding existing pages to po_translatable_pages: OK
    • 

  • removing existing pages from po_translatable_pages: OK
    • 

  • adding a language to po_slave_languages: OK
    • 

  • removing a language from po_slave_languages: OK
    • 

  • changing po_master_language: OK
    • 

  • replacing po_master_language with a language previously part of
po_slave_languages: needs two rebuilds, but OK (this is quite
a perverse test actually)
    • 



Creating/deleting/renaming pages


All cases of master/slave page creation/deletion/rename, both via RCS
and via CGI, have been tested.


Misc


    

  • general test with usedirs disabled: OK
    • 

  • general test with indexpages enabled: not OK
    • 

  • general test with po_link_to=default with userdirs enabled: OK
    • 

  • general test with po_link_to=default with userdirs disabled: OK
    • 



Misc. bugs


Documentation


Maybe write separate documentation depending on the people it targets:
translators, wiki administrators, hackers. This plugin may be complex
enough to deserve this.
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