postpone 0.3.0

An implementation of lazy strings. Can be used in combination with gettext for the translation of web apps.

It’s less beautiful than speaklater (an other implementation of lazy strings), but I wanted lazy strings that work even if a single thread interleaves the processing of many http requests (this happens with async frameworks).

postpone doesn’t rely on a global state. And it doesn’t use the thread.local() trick that speaklater uses either.

Example of use:

>>> from postpone import evalr, LazyString as _

>>> translations = {
        "Order {item}.": "Commander {item}.",
        "Take a nap": "Faire une sieste",
        "Stare at the wall for %s minutes.": "Fixer le mur pendant %s minutes." ,
        "a new pillow": "un nouvel oreiller"
    }

>>> tasklist = [
        _("Order {item}.").format(item = _("a new pillow")),
        _("Take a nap") + '!',
        _("Stare at the wall for %s minutes.") % 30
    ]

>>> evalr(tasklist, translations.get)
['Commander un nouvel oreiller.', 'Faire une sieste!', 'Fixer le mur pendant 30 minutes.']

evalr walks python dictionaries, lists, tuples or sets and apply a function to all the strings wrapped inside a LazyString object.

To apply a function to the strings inside a single expression, you can use the eval method:

>>> s = _("Take a nap") + '!'

>>> s.eval(str.upper)
'TAKE A NAP!'

>>> s.eval(translations.get)
'Faire une sieste!'

Or, again, the evalr function

>>> evalr(_("a new pillow").capitalize(), translations.get)
'Un nouvel oreiller'

For most projects containing more than a few strings or languages, you’ll probably want to use the gettext module to supply you with a translation function.

import gettext
translation = gettext.translation("myproject", "./locale", ["fr"])
translated_tasklist = evalr(tasklist, translation.ugettext)

GitHub repo: https://github.com/leforestier/postpone