I have prototyped desugared version of callable objects here: https://gist.github.com/2312621
I could not use short object syntax and unnamed method as proposed in original post, so I used regular object syntax and `new` as method name for unnamed `method`. I tried to illustrates that callable objects may be more elegant alternative to classes specially in combination with `<|` (which I expressed as `extend` function). Regards -- Irakli Gozalishvili Web: http://www.jeditoolkit.com/ On Wednesday, 2012-04-04 at 24:56 , David Bruant wrote: > Le 04/04/2012 02:41, Irakli Gozalishvili a écrit : > > > > > > On Tuesday, 2012-04-03 at 14:07 , David Bruant wrote: > > > > > Le 03/04/2012 22:00, Irakli Gozalishvili a écrit : > > > > Here is more or less what I have in mind: > > > > https://gist.github.com/2295048 > > > > > > > > // class > > > > var Point = { > > > > (x, y) { > > > > this.getX = { () { return x; } } > > > > this.getY = { () { return x; } } > > > > } > > > > > > > > toString() { > > > > return '<' + this.getX() + ',' + this.getY() + '>'; > > > > } > > > > } > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Interesting new function syntax. > > > The prototype and function body could even be declared together. What > > > about 'length'? > > > > > > > Also such callable objects provide shorter alternative to current > > > > function syntax: > > > > // shorter than function > > > > > > > > numbers. > > > > filter({ (x) { return x % 2 } }). > > > > // maybe single expression can be even shorter like arrow functions ? > > > > map({ (x) x * x }). > > > > forEach({ (x) { this.add(x) } }, that); > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > +1 > > > > > > > Also this would allow interesting APIs similar to those found in > > > > clojure: > > > > > > > > // maps / sets similar like in clojure ? > > > > var map = WeakMap(), key = {}, value = {}; > > > > > > > > map.set(key, value); > > > > map(key) // => value > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > So far so good. > > > > > > > key(map) // => value This cannot work for backward-compat reasons. In > > > > ES1-5, "key = {}" creates a regular (non-callable) object. > > > > > > > > > Well I did not suggested it should be backwards compatible, also nor > > classes nor shorter object syntax is backwards compatible. > They are to the extent that they throw an error for being invalid syntax in > previous version. This is the case for your proposal and that's a good thing > since that's the back door to introducing new features. > However, proposals should be backward compatible in semantics. > > In your case: > > var map = WeakMap(), key = {}, value = {}; > map.set(key, value); > map(key) // => value > key(map) // => value > > since key is callable, you have (typeof key === 'function') while ES5 > requires (typeof key === 'object') for objects that are constructed with > '{}'. There is code out there that relies on typeof for argument shifting: > 'if the first argument is a function, use that as callback, otherwise, use > the second argument (first argument being an option non-callable object)'. > There is this pattern all over the place in the mongodb node client as in > https://github.com/christkv/node-mongodb-native/blob/master/lib/mongodb/collection.js#L85 > In other cases, to pass a handler, some API check if the argument if an > object and in that case use the 'handle' property or use the function is what > has been passed is callable. > So, preserving typeof invariants regarding 'object'/'function' is crucial to > backward compatibility. > > Likewise for arrays. In ES1-5, (typeof [] === 'object') and the suggested > semantics of your proposal would break that. > > As far as I'm concerned, just the object-literal version of function is a > brilliant idea, no need for the additional semantics. > > David
_______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
