Helpers

It’s time to resolve the problem with indefinite article forms from The Problem or “Why do we need another i18n & l10n solution?” topic. The code is very simple:

def a(word):
    if word[0].lower() in ('a', 'e', 'i', 'o', 'u'):
        return 'an'
    return 'a'

Note

Yes, I’m cheating here. There is a lot of exceptions. For example, “a user”.

So, you can include it directly in your filter, but it will be better to make this code reusable.

# coding: utf-8

from h10n import Translator


def a(lang, country):
    if lang != 'en':
        raise ValueError('Unsupported language "{0}"'.format(lang))

    def helper_a(word):
        if word[0].lower() in ('a', 'e', 'i', 'o', 'u'):
            return 'an'
        return 'a'
    return helper_a

locales = {
    'en-US': {
        'message': {
            '__helper__': {
                'a': '__main__:a',
            },
            'removed': {
                'filter': """
                    $object = self.locale['object'][$object].format()
                """,
                'msg': u'{object} has been successfully removed'
            },
            'choose': {
                'filter': """
                    $object = self.locale['object'][$object].format().lower()
                    $an = helper.a($object)
                """,
                'msg': u'Please, choose {an} {object} for removal'
            }
        },
        'object': {
            'article': u'Article',
            'comment': u'Comment',
        },
    },
    'ru-RU': {
        'message': {
            'removed': {
                'filter': """
                    $object = self.locale['object'][$object]
                    $gender = $object.gender
                    $object = $object.format()
                """,
                'key': '{gender}',
                'msg': {
                    'm': u'{object} успешно удален',
                    'f': u'{object} успешно удалена',
                    'n': u'{object} успешно удалено',
                }
            }
        },
        'object': {
            'article': {
                'msg': u'Статья',
                'gender': 'f',
            },
            'comment': {
                'msg': u'Комментарий',
                'gender': 'm',
            },
        },
    },
}
t = Translator(locales=locales, default='en-US')

assert(t.translate('message:choose', 'Choose an object', object='article') ==
       u'Please, choose an article for removal')
assert(t.translate('message:choose', 'Choose an object', object='comment') ==
       u'Please, choose a comment for removal')

t.lang = 'ru'
assert(t.translate('message:choose', 'Choose an object', object='article') ==
       u'Please, choose an article for removal')
assert(t.translate('message:choose', 'Choose an object', object='comment') ==
       u'Please, choose a comment for removal')

Take a notice to __helper__ key in message catalog. It is not a message definition, it’s a helper namespace one. Helper namespace is provided as global value during filter compilation. So, you can get access to it from filter using helper identifier.

Keys of helper namespace definition dictionary become aliases of helpers. Values must be Python names of helper factories. The format of entry point from pkg_resources is used for these names, i.e. name is defined as package.name:factory.

Helper factory must be a callable, which accept two positional arguments: language and country. The returned value of factory is used by helper namespace as helper. There are no requirements of how to use passed arguments or which value to return.

Here we created one helper a in helper namespace, which is constructed by factory helper_a from current file. Take a notice, helper usage is limited by English language only.