On 12/19/2013 02:56 AM, Alex Russell wrote: > On Wed, Dec 18, 2013 at 3:32 PM, Ѓорѓи Ќосев <[email protected] > <mailto:[email protected]>> wrote: > > I understand that adding branding to promises is impossible at this > point, as it would break backward compatibility with all existing > implementations. > > > That wasn't the overriding consdieration. I don't care if we don't > have a-priori compatibility. The bigger issue is the lack of symbol > infrastructure in the language and the inability to polyfill if we do. > I've long argued for "ghetto branding" (something less foot-gun-ish > than an extractable then callable), but in the interest of harmony, > was not willing to fight for the better design at the end. > This doesn't need symbols at all, and it could be considered a "bugfix" addition - there is still time for those, I believe? It would make `.then` in the method name position less of a language keyword. Without breaking compatibility with existing implementations. It will also pave the path towards a future where most implementations inherit from built in promises and those that don't set their `prototype.__notPromise__ = false`,
If (and when) such a future arrives, the switch can be potentially flipped to assume `true` instead of `false`, thereby essentially removing the quirk from the language - completely. > Our primary goal here needs to be shipping something ASAP. All other concerns are, in the scheme of things, irrelevant.' > > We're already half a year late on this. Should the language really ban all objects from using `.then`, forever? Should it force library authors to face the decision: - my objects remain incompatible with promises (cannot be returned by them), or - rename `.then` method, do a massive refactor, also force all my users to do a massive refactor Why not provide a harmless third option? - add __notPromise__ flag to my prototype to tell promises not to assimilate these objects
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