Le 31 juil. 2013 à 20:23, "Tab Atkins Jr." <[email protected]> a écrit :
> > The first issue still up for community discussion involves the > definition of "promise-like". > > We'd like the definition to be: (a) a Promise or subtype, or (b) a > branded non-Promise (with the branding done via Symbol or similar). > Promises/A+ wants the branding to be done via a method named "then" > (the "thenable" concept). > > This, unfortunately, goes directly against TC39 practices in a number > of other areas, such as iterators, where we don't want short string > names as branding due to the possibility of collision. (In the case > of "then", collision isn't a possibility, it's a certainty - we *know* > there are libraries out there today that put a "then" method on their > objects without referring to Promises.) Thoughts? I suggest an @@isPromise builtin symbol, which works the same way as @@isRegExp in the ES6 spec [1]: An object is reputed to be a promise if and only if it has a property (either own or inherited) named @@isPromise. And `Promise.prototype` has initially an @@isPromise own property, so that instances of subclasses of `Promise` are recognised as promises. (With this solution, you have not to choose between subclassing or branding, but you have the both. :-) ) —Claude [1] search the occurrences of @@isRegExp in: http://people.mozilla.org/~jorendorff/es6-draft.html
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
