On Jan 3, 2012, at 4:31 PM, Gavin Barraclough wrote: > On Jan 3, 2012, at 3:27 PM, Brendan Eich wrote: > >> You're proposing that we require 'let' be only at the start of statements? >> If so, then destructuring is problematic: >> >> foo(); >> let [x] = y; >> >> Did that last line destructure the property named '0' of the object denoted >> by y into a let-bound x, or was it old, pre-ES6 code that stored y into the >> x'th element of an object denoted 'let'? In either case the 'let' is at the >> start of a statement. >> >> /be > > Based on the draft of the spec I have, I don't think that is an actual > ambiguity here (albeit naming an array 'let' could be very confusing!). > This could of course either be an error in my reading of the spec, or a bug > in the current draft of the grammar. :-) > > The rules for destructuring give: > > ArrayBindingPattern : > [ Elision<opt> BindingRestElement<opt> ] > [ BindingElementList , Elision<opt> BindingRestElement<opt> ] > > Note the literal comma required after any BindingElementList - as I parse the > grammar your example is not valid ES6, to destructure the first element from > an array you would have to write: > > foo(); > let [x,] = y;
No, the grammar is based on ArrayLiteral and produces the same "shapes", just with identifiers in the value positions. See the first right-hand side, interpreted with no Elision but with a BindingRestElement (which produces BindingIdentifier). /be _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
