312 lines
10 KiB
Markdown
312 lines
10 KiB
Markdown
[[!template id=plugin name=po core=0 author="[[intrigeri]]"]]
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[[!tag type/format]]
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This plugin adds support for multi-lingual wikis, translated with
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gettext, using [po4a](http://po4a.alioth.debian.org/).
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It depends on the Perl `Locale::Po4a::Po` library (`apt-get install po4a`).
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Introduction
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============
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A language is chosen as the "master" one, and any other supported
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language is a "slave" one.
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A page written in the "master" language is a "master" page. It can be
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of any page type supported by ikiwiki, except `po`. It does not have to be
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named a special way: migration to this plugin does not imply any page
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renaming work.
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Example: `bla/page.mdwn` is a "master" Markdown page written in
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English; if `usedirs` is enabled, it is rendered as
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`bla/page/index.en.html`, else as `bla/page.en.html`.
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Any translation of a "master" page into a "slave" language is called
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a "slave" page; it is written in the gettext PO format. `po` is now
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a page type supported by ikiwiki.
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Example: `bla/page.fr.po` is the PO "message catalog" used to
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translate `bla/page.mdwn` into French; if `usedirs` is enabled, it is
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rendered as `bla/page/index.fr.html`, else as `bla/page.fr.html`
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Configuration
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=============
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Supported languages
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-------------------
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`po_master_language` is used to set the "master" language in
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`ikiwiki.setup`, such as:
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po_master_language => { 'code' => 'en', 'name' => 'English' }
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`po_slave_languages` is used to set the list of supported "slave"
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languages, such as:
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po_slave_languages => { 'fr' => 'Français',
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'es' => 'Castellano',
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'de' => 'Deutsch',
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}
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Decide which pages are translatable
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-----------------------------------
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The `po_translatable_pages` setting configures what pages are
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translatable. It is a [[ikiwiki/PageSpec]], so you have lots of
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control over what kind of pages are translatable.
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The `.po` files are not considered as being translatable, so you don't need to
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worry about excluding them explicitly from this [[ikiwiki/PageSpec]].
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Internal links
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--------------
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The `po_link_to` option in `ikiwiki.setup` is used to decide how
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internal links should be generated, depending on web server features
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and site-specific preferences.
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### Default linking behavior
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If `po_link_to` is unset, or set to `default`, ikiwiki's default
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linking behavior is preserved: `\[[destpage]]` links to the master
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language's page.
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### Link to current language
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If `po_link_to` is set to `current`, `\[[destpage]]` links to the
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`destpage`'s version written in the current page's language, if
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available, *i.e.*:
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- `foo/destpage/index.LL.html` if `usedirs` is enabled
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- `foo/destpage.LL.html` if `usedirs` is disabled
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### Link to negotiated language
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If `po_link_to` is set to `negotiated`, `\[[page]]` links to the
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negotiated preferred language, *i.e.* `foo/page/`.
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(In)compatibility notes:
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- if `usedirs` is disabled, it does not make sense to set `po_link_to`
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to `negotiated`; this option combination is neither implemented
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nor allowed.
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- if the web server does not support Content Negotiation, setting
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`po_link_to` to `negotiated` will produce a unusable website.
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Server support
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==============
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Apache
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------
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Using Apache `mod_negotiation` makes it really easy to have Apache
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serve any page in the client's preferred language, if available.
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This is the default Debian Apache configuration.
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When `usedirs` is enabled, one has to set `DirectoryIndex index` for
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the wiki context.
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Setting `DefaultLanguage LL` (replace `LL` with your default MIME
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language code) for the wiki context can help to ensure
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`bla/page/index.en.html` is served as `Content-Language: LL`.
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lighttpd
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--------
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lighttpd unfortunately does not support content negotiation.
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**FIXME**: does `mod_magnet` provide the functionality needed to
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emulate this?
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Usage
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=====
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Templates
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---------
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The `ISTRANSLATION` and `ISTRANSLATABLE` variables can be used to
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display things only on translatable or translation pages.
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### Display page's versions in other languages
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The `OTHERLANGUAGES` loop provides ways to display other languages'
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versions of the same page, and the translations' status.
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One typically adds the following code to `templates/page.tmpl`:
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<TMPL_IF NAME="OTHERLANGUAGES">
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<div id="otherlanguages">
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<ul>
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<TMPL_LOOP NAME="OTHERLANGUAGES">
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<li>
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<a href="<TMPL_VAR NAME="URL">"><TMPL_VAR NAME="LANGUAGE"></a>
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<TMPL_UNLESS NAME="MASTER">
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(<TMPL_VAR NAME="PERCENT"> %)
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</TMPL_UNLESS>
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</li>
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</TMPL_LOOP>
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</ul>
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</div>
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</TMPL_IF>
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The following variables are available inside the loop (for every page in):
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- `URL` - url to the page
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- `CODE` - two-letters language code
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- `LANGUAGE` - language name (as defined in `po_slave_languages`)
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- `MASTER` - is true (1) if, and only if the page is a "master" page
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- `PERCENT` - for "slave" pages, is set to the translation completeness, in percents
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### Display the current translation status
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The `PERCENTTRANSLATED` variable is set to the translation
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completeness, expressed in percent, on "slave" pages.
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One can use it this way:
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<TMPL_IF NAME="ISTRANSLATION">
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<div id="percenttranslated">
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<TMPL_VAR NAME="PERCENTTRANSLATED">
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</div>
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</TMPL_IF>
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Additional PageSpec tests
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-------------------------
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This plugin enhances the regular [[ikiwiki/PageSpec]] syntax with some
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additional tests that are documented [[here|ikiwiki/pagespec/po]].
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Automatic PO file update
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------------------------
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Committing changes to a "master" page:
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1. updates the POT file and the PO files for the supported languages;
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the updated PO files are then put under version control
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2. triggers a refresh of the corresponding HTML slave pages
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Also, when the plugin has just been enabled, or when a page has just
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been declared as being translatable, the needed POT and PO files are
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created, and the PO files are checked into version control.
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Discussion pages
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----------------
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Discussion should happen in the language in which the pages are written for
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real, *i.e.* the "master" one. If discussion pages are enabled, "slave" pages
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therefore link to the "master" page's discussion page.
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Translating
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-----------
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One can edit the PO files using ikiwiki's CGI (a message-by-message interface
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could also be implemented at some point).
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If [[tips/untrusted_git_push]] is setup, one can edit the PO files in one's
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preferred `$EDITOR`, without needing to be online.
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TODO
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====
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OTHERLANGUAGES dependencies
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---------------------------
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Pages using `OTHERLANGUAGES` depend on any "master" and "slave" pages
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whose status is being displayed. It is supposed to trigger dependency
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loops, but no practical bugs were noticed yet.
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Should pages using the `OTHERLANGUAGES` template loop be declared as
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linking to the same page in other versions? To be rigorous, they
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should, but this may clutter the backlinks.
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Security checks
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---------------
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- `refreshpofiles` uses `system()`, whose args have to be checked more
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thoroughly to prevent any security issue (command injection, etc.).
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> Always pass `system()` a list of parameters to avoid the shell.
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> I've checked in a change fixing that. --[[Joey]]
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- `refreshpofiles` and `refreshpot` create new files; this may need
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some checks, e.g. using `IkiWiki::prep_writefile()`
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> Yes, it would be ideal to call `prep_writefile` on each file
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> that they write, beforehand. This way you'd avoid symlink attacks etc to the
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> generated po/pot files. I haven't done it, but it seems pretty trivial.
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> --[[Joey]]
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- Can any sort of directives be put in po files that will
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cause mischief (ie, include other files, run commands, crash gettext,
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whatever).
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- Any security issues on running po4a on untrusted content?
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gettext/po4a rough corners
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--------------------------
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- fix infinite loop when synchronizing two ikiwiki (when checkouts
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live in different directories): say bla.fr.po has been updated in
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repo2; pulling repo2 from repo1 seems to trigger a PO update, that
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changes bla.fr.po in repo1; then pushing repo1 to repo2 triggers
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a PO update, that changes bla.fr.po in repo2; etc.; fixed in
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`629968fc89bced6727981c0a1138072631751fee`?
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- new translations created in the web interface must get proper charset/encoding
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gettext metadata, else the next automatic PO update removes any non-ascii
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chars; possible solution: put such metadata into the Pot file, and let it
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propagate; should be fixed in `773de05a7a1ee68d2bed173367cf5e716884945a`, time
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will tell.
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Misc. improvements
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------------------
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### preview
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preview does not work for PO files.
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### automatic POT/PO update
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Use the `change` hook instead of `needsbuild`?
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### page titles
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Use nice page titles from meta plugin in links, as inline already does. This is
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actually a duplicate for
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[[bugs/pagetitle_function_does_not_respect_meta_titles]], which might be fixed
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by something like [[todo/using_meta_titles_for_parentlinks]].
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### websetup
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Which configuration settings are safe enough for websetup?
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> I see no problems with `po_master_language` and `po_slave_languages`
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> (assuming websetup handles the hashes correctly). Would not hurt to check
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> that the values of these are legal language codes, in `checkconfig`.
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> `po_translatable_pages` seems entirely safe. `po_link_to` w/o usedirs
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> causes ikiwiki to error out. If it were changed to fall back to a safe
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> setting in this case rather than error, it would be safe.
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> --[[Joey]]
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### parentlinks
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When the wiki home page is translatable, the parentlinks plugin sets
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`./index.html` as its translations' single parent link. Ideally, the home page's
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translations should get no parent link at all, just like the version written in
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the master language.
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### backlinks
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If a given translatable `sourcepage.mdwn` links to \[[destpage]],
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`sourcepage.LL.po` also link to \[[destpage]], and the latter has the master
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page *and* all its translations listed in the backlinks.
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Translation quality assurance
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-----------------------------
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Modifying a PO file via the CGI must be forbidden if the new version
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is not a valid PO file. As a bonus, check that it provides a more
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complete translation than the existing one.
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A new `cansave` type of hook would be needed to implement this.
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Note: committing to the underlying repository is a way to bypass
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this check.
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