On May 18, 2011, at 12:41 AM, Dmitry A. Soshnikov wrote:
> On 18.05.2011 6:50, Allen Wirfs-Brock wrote:
>>
>> We had so much fun with feedback on my Unicode proposal I just have open
>> another one up for list feed back:
>>
>> An updated version of the "prototype for" (formerly proto) operator proposal
>> is at http://wiki.ecmascript.org/doku.php?id=strawman:proto_operator
>>
>
> Just a small note on:
>
> "There are many other possible special character alternates to <|. For
> example, |>, ^^, *>, &>, ^|, <|-, etc. It isn’t clear that any of these is
> more meaningful or mnemonic than <|."
>
> Perhaps just "less than" would be enough? Why we need two symbols? It's by
> the way, a real implementation of subclassing in Ruby:
>
>
< already has a meaning for operands that are arbitrary objects. It applies
valueOf and/or toString to the operands and then compares the results.
> And also: what's happened to meta-properties in initialisers? It seems to me
> that having them we get also the ability not only to specify the proto, but
> also other control attributes for properties and to the object. And since
> #-symbol has changed its semantics, and instead ->-functions (or probably
> Ruby's blocks) are on agenda instead, maybe we may use # exactly for meta
> properties?
>
The most common use case for meta properties was to set [[Prototype]]. That
solution worked for object literals and array literal but didn't extend to
functions, regexps, or other literal forms. <| does. The other uses of meta
properties sealed, frozen, closed would probably be used infrequently enough
that the Object functions are good enough:
let bar = Object.preventExtensions(foo <| {y:20});
Also there were some concerns about possible syntactic conflicts between the
proposed meta-property syntax and E4X features (I know...but some people
care)...
Overall, <| seems like a simpler solution that is more general for the most
important use case.
Allen
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