How to bind a text domain to a local folder for gettext under GTK3

In PyGtk you can use Gtk.Builder too. Accordingly to the PyGtk Gtk.Builder documentation:

http://developer.gnome.org/pygtk/stable/class-gtkbuilder.html#properties-gtkbuilder

The translation domain used when translating property values that have
been marked as translatable in interface descriptions. If the
translation domain is None, GtkBuilder uses gettext(), otherwise
dgettext(). Default value: None

That is, Gtk.Builder uses dgettext() from “C library”. The problem is that Python’s gettext module, function bindtextdomain(), for some reason unknown to me, don’t set the “C library”. The option is to use the locale module that also exposes that interface. From the Python locale module documentation:

http://docs.python.org/library/locale#access-to-message-catalogs

The locale module exposes the C library’s gettext interface on systems
that provide this interface. It consists of the functions gettext(),
dgettext(), dcgettext(), textdomain(), bindtextdomain(), and
bind_textdomain_codeset(). These are similar to the same functions in
the gettext module, but use the C library’s binary format for message
catalogs, and the C library’s search algorithms for locating message
catalogs.

Python applications should normally find no need to invoke these
functions, and should use gettext instead. A known exception to this
rule are applications that link with additional C libraries which
internally invoke gettext() or dcgettext(). For these applications, it
may be necessary to bind the text domain, so that the libraries can
properly locate their message catalogs.

Which, is the current case. What a hack :S

This will do it, file test.py:

from gi.repository import Gtk
from os.path import abspath, dirname, join, realpath
import gettext
import locale

APP = 'myapp'
WHERE_AM_I = abspath(dirname(realpath(__file__)))
LOCALE_DIR = join(WHERE_AM_I, 'mo')

locale.setlocale(locale.LC_ALL, '')
locale.bindtextdomain(APP, LOCALE_DIR)
gettext.bindtextdomain(APP, LOCALE_DIR)
gettext.textdomain(APP)
_ = gettext.gettext

print('Using locale directory: {}'.format(LOCALE_DIR))

class MyApp(object):

    def __init__(self):
        # Build GUI
        self.builder = Gtk.Builder()
        self.glade_file = join(WHERE_AM_I, 'test.glade')
        self.builder.set_translation_domain(APP)
        self.builder.add_from_file(self.glade_file)

        print(_('File'))
        print(_('Edit'))
        print(_('Find'))
        print(_('View'))
        print(_('Document'))

        # Get objects
        go = self.builder.get_object
        self.window = go('window')

        # Connect signals
        self.builder.connect_signals(self)

        # Everything is ready
        self.window.show()

    def main_quit(self, widget):
        Gtk.main_quit()

if __name__ == '__main__':
    gui = MyApp()
    Gtk.main()

My Glade file test.glade:

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <object class="GtkWindow" id="window">
    <property name="can_focus">False</property>
    <property name="window_position">center-always</property>
    <property name="default_width">400</property>
    <signal name="destroy" handler="main_quit" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkLabel" id="label1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">File</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Edit</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label3">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Find</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label4">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">View</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">3</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label5">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Document</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">4</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Remember to create the mo in mo/LANG/LC_MESSAGES/myapp.mo based on .po extracted with:

xgettext --keyword=translatable --sort-output -o en.po test.glade

What it looks like:

Kind regards