Le 26/04/2013 00:21, Claus Reinke a écrit :
I'm still wading through the various issue tracker threads, but only two
concrete rationales for flattening nested Promises have emerged so far:
1 "library author doesn't want nested Promises."
2 crossing Promise library boundaries can create unwanted nesting
Perhaps you didn't read my post then?
https://mail.mozilla.org/pipermail/es-discuss/2013-April/030192.html
I've shared experience on why flattening promises are convenient (easier
refactoring, easier to reason about) and why non-flattening would be
annoying (impose some sort of boilerplate somewhere to get to the actual
value you're interested in).
Kevin Smith made a point that I believe is underestimated by
non-flattening advocates:
I think flattening is also tied inextricably to the fact that promises
are a featureless wrapper for values. Nobody cares about
promises-as-values because of this featureless-ness. And because they
are completely uninteresting as values, programmers can think
"straight through" to the eventual value.
This is highly simplifying for the programmer, especially in the
context of complex asynchronous data flows.
From experience, I couldn't care less for a wrapper for a wrapper for a
value. I just want wrappers and values. Promises are just async boxes.
Beyond rationale, I'd like non-flattening advocates to show use cases
where a Future<Future<T>> can be useful; more useful than just Future<T>
and T.
David
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