On Tue, May 21, 2013 at 9:20 PM, Ron Buckton <[email protected]> wrote: > What if the default Map prototype had a configurable but non-writable data > property for a @@coerceKey symbol that pointed to a default coercion > function. You could subclass Map and provide your own @@coerceKey > implementation. Then Map.prototype.set.call() would be forced to run the > custom coercion function. > > A @@coerceKey override could be used to coerce keys from one type to > another, or to provide key validation if you want keys in a specific format. > By providing a default implementation that is basically an identity > function, you maintain the same current expectations for Map. This then > gives developers the ability to further customize the behavior of Map in > subclasses, giving the class more flexibility. > > If that were the case, there could also be a @@coerceValue symbol on > Map.prototype as well as Set.prototype. Possibly even Array.prototype as > well for Array subclasses, as a means of limiting array contents to a > specific type. The coercion functions could also be used to allow a subclass > to Mark itself as read-only and throw on attempts at modification. Default > implementations could verify whether the coercion function has changed from > the default and skip the coercion calls as a performance optimization.
These aren't bad ideas, and they get me most of the way to where I need to be. I still need some way to detect when an entry is added/modified/deleted, so I can update the style rule it's associated with. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
