django.utils.functional.lazy fails for datetime.date.today

[anonymous]

When attempting to create a lazily evaluated version of datetime.date.today -- lazy(datetime.date.today, datetime.date) -- the lazy function returns an error because datetime.date.today does not have a __dict__ attribute. This used to work with the old version of lazy (my old version was from r4944).

[Malcolm Tredinnick]

Since lazy() is designed for internal use and the primary use is translation stuff, the recent performance improvements which may have caused this are well worth the trade-off. So if somebody wants to write a patch to handle things like this that does not increase memory usage or impact performance, we'd certainly take it (and I can imagine such a patch would be possible).

[Aymeric Augustin]

There's a patch, now we need tests, and a performance benchmark to ensure the impact is limited — see Malcolm's comment.

[Claude Paroz]

In current code, this is passing with success:

    import datetime
    lazy_today = lazy(datetime.date.today, datetime.date)
    self.assertEqual(lazy_today(), datetime.date.today())