Re: I18n in plugin

[Federico Mena Quintero <federico ximian com>]

On Mon, 2006-05-22 at 14:06 +0800, Yang Hong wrote:

> There are many applications use plugin based architecture to expand it's
> function, such as Evolution (EPlugin), Anjuta 2.x, Gedit, Gaim,
> Xchat-gnome, etc. The problem is that if the plugins was released
> outside of the main app, the user interface of the plugin is NOT I18n
> able. even I added bindtextdomain(...) and bind_textdomain_codeset (...)
> in the initialize code of the plugin.

Plugins which are loaded in the same address space as the main process
need to use bindtextdomain() and dgettext() instead of the plain
textdomain() and gettext().

bindtextdomain("my_plugin", "/usr/share/locale/myplugin/")

dgettext ("my_plugin", "string to translate")

This is so that the gettext machinery will know that your strings don't
come from the domain of the main program, but from your plugin's own
domain.

If you #include <glib/gi18n-lib.h>, you'll get

	#define _(x) dgettext(GETTEXT_PACKAGE, x)

which makes it easy to use dgettext() automatically.  Note that you of
course have to define GETTEXT_PACKAGE elsewhere, probably in your
Makefile:

	CFLAGS="-DGETTEXT_PACKAGE=my_plugin"

> Yestoday, I got a remove-duplicates plugin for evolution 2.4 from
> #342378 [2], after some hack it for evolution 2.6, added LINGUAS suport,
> added zh_CN translate [3], intalled it and got a untranslate menu item
> "Remove duplicates". and then I found that there is even not point to
> add the bindtextdomain for it, there's only one entrance for this
> plugin's functional. how can it could be i18ned?

I don't know about that bug, but keep the following in mind.

Some plug-in APIs let you pass strings to the main program, and then the
main program will call gettext() on them.  *This is wrong*, because
gettext() will assume the domain of the program, while you almost
certainly want the domain of your own plugin.

In this case, the API needs to be changed to let you pass a domain along
with the strings, or something like that:

  plugin_handle = plugin_register (plugin_name, domain_for_plugin);

  /* Uses domain_for_plugin (stored in plugin_handle)
   * when calling dgettext() */
  plugin_add_menu_item (plugin_handle, "Interesting command");

Good luck,

  Federico