What is the best way to internationalize a Python app with multiple i18n domains?

Question

I'm internationalizing a Python application, with two goals in mind:

1. The application loads classes from multiple packages, each with its own i18n domain. So modules in package A are using domain A, modules in package B are using domain B, etc.

2. The locale can be changed while the application is running.

Python's gettext module makes internationalizing a single-domain single-language application very easy; you just set the locale, then call gettext.install(), which finds the right Translation and installs its ugettext method in the global namespace as _. But obviously a global value only works for a single domain, and since it loads a single Translation, it only works for that locale.

I could instead load the Translation at the top of each module, and bind its ugettext method as _. Then each module would be using the _ for its own domain. But this still breaks when the locale is changed, because _ is for the wrong locale.

So I guess I could load the correct ugettext at the top of every function, but that seems awfully cumbersome. An alternative would be to still do it per-module, but instead of binding ugettext, I would substitute my own function, which would check the current locale, get its Translation, and forward the string to it. Does anyone have a cleaner solution?

Answer 1

how about you bind _ to a function roughly like this (for each module):

def _(message):
    return my_gettext(__name__, message)

This allows you to use gettext while at the same time perform any lookup on a per-module-per-call-base that allows you to switch locale as well.