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Re: Unordered setsmaps, for when ordering is hard/expensive/unwanted?

From: Brendan Eich <brendan@secure.meer.net>
Date: Mon, 02 Sep 2013 12:57:02 -0700
Message-ID: <5224ED8E.2070908@secure.meer.net>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Boris Zbarsky <bzbarsky@mit.edu>, "public-script-coord@w3.org" <public-script-coord@w3.org>
Tab Atkins Jr. wrote:
> On Mon, Sep 2, 2013 at 12:25 PM, Brendan Eich<brendan@secure.meer.net>  wrote:
>> >  No, but thanks for your patience going through why it's hard to require a
>> >  canonical order. We'll have to do one or both of:
>> >
>> >  * Leave things unspecified.
>> >
>> >  * Add the random starting index_a la_  Go, as Tab suggests.
>> >
>> >  In either case, we would hope that the problem Bjoern cites doesn't come to
>> >  pass (that one implementation's order becomes a de-facto standard). Without
>> >  evidence I have a hard time believing either bullet-point affects the
>> >  likelihood of that problem arising.
>
> Well, we know from experience that the first one is a no-go - we
> always end up with compat pain, sometimes getting bad enough to force
> a de facto order to become a de jure one.

That's not a "no go". We don't like it but sometimes, and I can defend a 
few in ECMA-262, underspecification is a net win.

Doing more here may not help (Bjoern's point) and definitely costs. It 
might be "worth a try", or not -- I'm not sure. What PRNG (Math.random? 
Hope not, should not be correlatable) or RBG (Crypto.getRandomValues)? 
Has anyone drafted a spec? We aren't using Go so we may not want to copy 
whatever it does in detail.

/be
Received on Monday, 2 September 2013 19:57:32 UTC

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