[gettext] How to change language at run-time

[pozz]

Il 15/06/2017 15:22, Peter Otten ha scritto:
> pozz wrote:
> 
>> I know I can load multiple gettext.translation:
>>
>>     it = gettext.translation('test', localedir="locale", languages=["it"])
>>     es = gettext.translation('test', localedir="locale", languages=["es"])
>>
>> and install one translation at run-time when I want at a later time
>> (when the user selects a new language):
>>
>>     it.install()
>> or
>>     es.install()
>>
>>
>> However the problem is that strings already translated are not
>> translated again when a new translation is installed.  So they stay at
>> the language selected during start-up and don't change after a new
>> install().
>>
>> One solution is to restart the application, but I think there's a better
>> and more elegant solution.
> 
> You need a way to defer the translation until the string is actually used.
> The documentation has a few ideas
> 
> https://docs.python.org/dev/library/gettext.html#deferred-translations
> 
> and here's another one -- perform the translation in the __str__ method of
> a custom class:
 > [...]


It's a nice trick. However you will have a string that isn't a string, 
but a class.  I think you can't use the class everywhere you can use a 
string.  For example, len() can't be called.