On Mon, May 20, 2013 at 10:27 PM, Domenic Denicola <[email protected]> wrote: > Hmm, so that invariant wouldn't hold? I assume `has` would be similarly > broken? Seems… not so Map like, besides perhaps having some operations with > the same name as Map's. > > Relevant: http://en.wikipedia.org/wiki/Liskov_substitution_principle
Let's ignore Liskov; I don't really care about subclassing, not least because being strictly Liskov-pure makes most subclasses invalid. The things I care about: * when someone asks "is this Map-like?" in an appropriately idiomatic JS way, they get a "yes" answer. * when someone adds a new function to Maps in an appropriately idiomatic JS way, the method also applies to this object * when JS expands the set of built-in methods for Map, it also gets applied to this object without me having to update my spec * for all the existing Map methods, I get identical/equivalent methods without having to manually redefine every single one of them All of these are easy to do if this is just a Map (or has Map on its prototype chain), but with a custom [[MapData]] whose behavior is defined by my spec. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
