Array.prototype.contains

Mark S. Miller erights at google.com
Sat Nov 3 18:15:32 PDT 2012


WeakMap.has is fine (and already speced) because the presence of the
association depends on the key. However, if the key is garbage, a strong
ref to the value does not preserve the association in the map.


On Sat, Nov 3, 2012 at 6:05 PM, Brendan Eich <brendan at mozilla.org> wrote:

> Is this true? I can see how enumeration and size would leak the GC
> schedule, but to test has or contains, you need a strong ref, which means
> the key or value cannot yet be garbage. If you have the capability, there's
> no non-determinism. What am I missing?
>
> /be
>
> Allen Wirfs-Brock wrote:
>
>>
>> On Nov 3, 2012, at 4:53 PM, Mark S. Miller wrote:
>>
>>  On Fri, Nov 2, 2012 at 5:26 PM, Allen Wirfs-Brock <allen at wirfs-brock.com<mailto:
>>> allen at wirfs-brock.com>**> wrote:
>>>
>>>
>>>     Also any reason contains should be provided for WeakMap? I not
>>>     seeing why it shouldn't be there too.
>>>
>>>
>>> Yes!
>>>
>>> The set of values actually contained by the WeakMap at any moment is
>>> non-deterministic, depending on the scheduling of gc. But this
>>> non-determinism is non-observable. WeakMap.contains would make it
>>> observable.
>>>
>>
>>
>> yup
>>
>>
>>
>>
>>> --
>>>     Cheers,
>>>     --MarkM
>>>
>>
>> ______________________________**_________________
>> es-discuss mailing list
>> es-discuss at mozilla.org
>> https://mail.mozilla.org/**listinfo/es-discuss<https://mail.mozilla.org/listinfo/es-discuss>
>>
>


-- 
    Cheers,
    --MarkM
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20121103/135b9141/attachment.html>


More information about the es-discuss mailing list