metglobal/django-exchange — pull request #15 by fergalwalsh (2013-12-09 11:17:26+00:00)
Title: Speed up repeated conversions between the same currency pairs

I have added a module level dict to keep a local cache of retrieved rates. Rates are first retrieved from here if possible before fetching from the external cache.

The dict is cleared when ```update_rates_cached``` is called so the locally cached rates will never be any older than the main cache.