Standardizing __proto__

Allen Wirfs-Brock allen at
Fri Mar 18 10:08:39 PDT 2011

There is a general problem of  supporting creation of  special behavior objects (EG, Boolean, RegExp, anything fronted by a Proxy(??)) with arbitrary prototypes that I'm looking at for a Harmony strawman.  However, I think in practice that this occurs very rarely for anything other than Array.

I would be ideal if TC39 could agree upon an Array.create proposal at its next meeting.  This would enable implementations to immediately move towards providing a standards path alternative to  what is probably the major use case for LHS __proto__.

Array create seems like a good interface for that particular use case even if the general solution that encompasses things other than Array ended up being something different.


On Mar 18, 2011, at 9:46 AM, Mike Shaver wrote:

> On Fri, Mar 18, 2011 at 9:29 AM, John-David Dalton
> <john.david.dalton at> wrote:
>> @Mike Shaver
>> For other possible uses please check out:
> Those all look like they are needing custom-initialization, not
> arbitrary mutation at any point.  Would you agree?  For symmetry with
> Object.create, you might want Boolean.create, Date.create and so
> forth, but that's still initialization-time, and TBH I would be
> surprised if there were actually many collisions between libraries
> that augment those prototypes.
> Preserving (or adding to other engines) arbitrary prototype chain
> mutation in order to work around name collisions seems wrong to me.
> Mutable proto just happened to be the hack that worked (though so did
> iframes), and I can't really find anything other than Fuse that uses
> it on the web today.  The solution to name collisions is simple
> modules, IMO, not monkeypatching of the builtin prototype hierarchy.
> I think you can also achieve what you want with Harmony proxies, so
> you'll have that option in the next edition of ES.
> Mike
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