[Python-Dev] PEP 3156 - Asynchronous IO Support Rebooted

[Nick Coghlan]

On Wed, Jan 9, 2013 at 11:14 AM, Yuriy Taraday <yorik.sar at gmail.com> wrote:
> 4. Why separate exception() from result() for Future class? It does the same
> as result() but with different interface (return instead of raise). Doesn't
> this violate the rule "There should be one obvious way to do it"?

The exception() method exists for the same reason that we support both
"key in mapping" and raising KeyError from "mapping[key]": sometimes
you want "Look Before You Leap", other times you want to let the
exception fly. If you want the latter, just call .result() directly,
if you want the former, check .exception() first.

Regardless, the Future API isn't really being defined in PEP 3156, as
it is mostly inheritied from the previously implemented PEP 3148
(http://www.python.org/dev/peps/pep-3148/#future-objects)

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia