On Jul 15, 2010, at 4:32 PM, Ken MacDonald wrote:
> @defer.inlineCallbacks
> def round_val(id, value, rule):
> """
> Return first element of round_value_and_percent
> """
> defer.returnValue(round_value_and_percent(id, value, 0, rule)[0])
> When I do:
> result = yield round_val(1, 2, 3)
>
> I get this: Deferred instance has no attribute '__getitem__'
>
> Clues appreciated!
@inlineCallbacks must decorate only generator functions.
Since 'yield' doesn't appear anywhere in the body of round_val (or, for that
matter, round_per) this code will break in other ways. Allen Short's
suggestion will fix your code because it added a 'yield', but you need to be
aware of this issue in case there are other such functions in the future that
don't actually handle any Deferreds.
Also, inlineCallbacks adds some overhead, and really should only be used when
the resulting code is easier to read. Personally, I think a simpler definition
of round_val would be simply
def round_val(id, value, rule):
"""
Return first element of round_value_and_percent
"""
return round_value_and_percent(id, value, 0, rule).addCallback(
lambda valueAndPercent: valueAndPercent[0]
)
no @inlineCallbacks required.
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