Scope of the TextDomains
ruby-gettext-scope
You can set the textdomains in a class/module. If the class can't find the textdomain in the class, the textdomain of the super class or nesting modules.
See the simple figure below.

Calling 'bindtextdomain' in the global area (line 2,3) isn't recomannded.
Keyword(s):
References:[Ruby-GetText-Package document for Developers]