On Jan 4, 2015 9:06 PM, Fred Schott <[email protected]> wrote: > > In Section B.3.1 on "__proto__ Property Names in Object Initializers" there > is a paragraph explaining when duplicate properties will result in a syntax > error. It says: > >> It is a Syntax Error if PropertyNameList of PropertyDefinitionList contains >> any duplicate entries for "__proto__" and at least two of those entries were >> obtained from productions of the form PropertyDefinition : PropertyName : >> AssignmentExpression . > > > Where PropertyName is defined as: > >> PropertyName[Yield,GeneratorParameter] : >> LiteralPropertyName >> [+GeneratorParameter] ComputedPropertyName >> [~GeneratorParameter] ComputedPropertyName[?Yield] >> >> LiteralPropertyName : >> IdentifierName >> StringLiteral >> NumericLiteral > > > That paragraph (using the definitions provided) seems to assert that it is a > syntax error if there are any duplicate uses of __proto__ with an > IdentifierName, StringLiteral, or ComputedPropertyName. To translate this > into an example, it seems to assert that in ES6 this is not valid: > >> var obj = { >> __proto__: somePrototype, >> ["__proto__"]: somePrototype >> } >> >> // Error: SyntaxError
No, this is not supposed to be a syntax error. > > > Is that correct? Step 6 of Section B.3.1 explicitly states that the computed > ["__proto__"] does not have the same special behavior as the literal > property. But from my understanding of other es-discuss topics & resources, > the restriction on duplicate "__proto__" properties also does not apply to > computed properties. If that is true, then the quoted paragraph above seems > to be incorrect or misleading. > > Can anyone clarify this? I may just be misunderstanding the docs and/or the > recent discussions. Or it could be that the definition has changed around > that quoted paragraph and it needs to be updated. The latter. Please file a bug at bugs.ecmascript.org _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
