Le 23/04/2013 15:53, Brendan Eich a écrit :
David Bruant wrote:
Le 23/04/2013 15:30, Allen Wirfs-Brock a écrit :
* { [ "__proto__" ]: .... } is not special in any way, and creates
a normal property named "__proto__".
I don't believe this is legal. Didn't we agree w to support [ ]
property keys that evaluate to symbols.
I don't know what the agreement is, but that would be wise to forbid
strings in [ ] propert keys given that ES6 introduces Maps which seem
to be a better host for dynamically generated string keys.
What?
Maps are for *abitrary values* as keys -- any type.
Objects have string-equated keys so far. In ES6 we sum symbol | string
as the property name type. There is no problem with the o = {[n]: v}
syntax for computed property name n (an expression, we argued about
wither /Expression/ or /AssignmentExpression/ but I forget the
outcome) resulting in either a symbol, or else a value equated to a
string as in object literals today.
From a language perspective, I agree o = {[n]: v} can work with n as a
string.
From a developer perspective, I wonder if this isn't confusing as it
provides another way to do something that's already possible.
o = {[n]: v}
If n is a string literal, developers might as well get rid of the
brackets. In all other cases, the following work already:
o = {};
o[n] = v;
If someone feels like doing:
o = {
[a]: v1,
[b]: v2,
[c]: v3,
[d]: v4,
}
Maybe what they want is a Map (dynamically computed strings) or an array
(fixed length).
I don't see a use case where dynamic key strings in object literals is a
good idea.
David
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