First, yes, relying of ES5 + WeakMap is fine, since we have a reliable and secure (though painful and leaky) WeakMap polyfill for ES5. However, even with that, how do you construct a function which can distinguish whether it is called with "new" or not?
On Wed, Aug 21, 2013 at 7:15 PM, Tab Atkins Jr. <[email protected]>wrote: > On Wed, Aug 21, 2013 at 7:13 PM, Domenic Denicola > <[email protected]> wrote: > > From: Tab Atkins Jr. [mailto:[email protected]] > > > >> Unless you wanted promise-likes to return fresh objects too? > > > > Yes, that is largely the use case for `Q`/`Promise.as`/whatever. Handing > it untrusted input, possible a non-promise, possibly a promise-like, > possibly a promise, and getting back a trusted promise. > > Okay, that makes sense. > > >> The only way to have a completely reliable type test is to use a > WeakSet to keep track of instances > > > > I believe this is what Mark's makeQ.js does. > > > >> Do you consider WeakMaps sufficient for polyfillability? > > > > I believe makeQ.js uses a WeakMap polyfill, so yes. > > Cool. > > ~TJ > -- Cheers, --MarkM
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