April 10 2014 Meeting Notes

[Mark S. Miller]

On Sat, Apr 26, 2014 at 2:52 PM, Brendan Eich <brendan at mozilla.org> wrote:

> Mark S. Miller wrote:
>
>> Regarding the points:
>>
>> #1 yes, we cannot provide one that's reliable, so let's not claim that it
>> is reliable.
>>
>
> Indeed it is not safe, even excluding yield, to assume finallys run in
> browser contexts, unless you can prove termination of trys (which is hard,
> right? Halting problem and all that).
>
>
>  #2 yes it does. I acknowledge that this is a genuine cost.
>>
>
> I think I can make your case stronger: without |return| one cannot be sure
> a generator iterator |it| parked at a yield won't resume some time later.
> To ensure that it is really "done", call it.return(). Might this be
> important for reasoning about security?
>

Plausible!



>
> BTW, return() should be idempotent. Is it?


Since .return takes an argument whose value is observable, I think not.

Hmmm. This is interestingly similar to multiple calls to resolve.


>
>  #3 for those rare cases where it is inappropriate, like this example,
>> better not to use a for/of anyway to make the unusualness of this code's
>> purpose more explicit.
>>
>
> Definitely -- given the implicit @@iterator call from (among other places)
> for-of constructs, it's best with for-of loops to avoid any reuse of the
> iterator later. Such hinky multi-loop consumption of a single iterator
> should be considered bad style. One can still do it, of course.
>
> /be
>



-- 
    Cheers,
    --MarkM
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