On Wed, Oct 3, 2012 at 2:07 PM, Herby Vojčík <[email protected]> wrote:
> > > Rick Waldron wrote: > >> >> >> On Wed, Oct 3, 2012 at 1:57 PM, Herby Vojčík <[email protected] >> <mailto:[email protected]>> wrote: >> >> >> >> Rick Waldron wrote: >> >> >> >> On Wed, Oct 3, 2012 at 12:56 PM, Herby Vojčík <[email protected] >> <mailto:[email protected]> >> <mailto:[email protected] <mailto:[email protected]>>> wrote: >> >> >> >> Nicholas C. Zakas wrote: >> >> After a little more experimenting with sets (still a >> really big >> fan!!), >> I've come across an interesting problem. Basically, I >> found >> myself using >> a set and then wanting to convert that into JSON for >> storage. >> JSON.stringify() run on a set returns "{}", because >> it's an object >> without any enumerable properties. I'm wondering if >> that's the >> correct >> behavior because a set is really more like an array >> than it is an >> object, and perhaps it would be best to define a >> toJSON() method for >> sets such as: >> >> Set.prototype.toJSON = function() { >> return Array.from(this); >> >> It depends... you should be able to reread it, so the best >> thing >> would proably be to use matching set of transformers for both >> stringify and parse. I personally would rather see >> something like >> { _Set_from_: Array.from(this) } >> here. >> >> }; >> >> >> >> The revived array can be passed as an arg to new Set(revived) : >> >> new Set(JSON.parse(s.toJSON())) >> >> >> I am talking about deep nested structure with (possibly) multiple >> sets all over. Your solution is unusable, you need to explicitly >> know where the arrayified sets are. >> >> >> Fair enough, my solution definitely doesn't scale. >> >> In that case, I'd say it's not the language's job to try and guess what >> the user code wanted to do with a serious of deeply nested, stringified >> arrays in a JSON string. Seems like a non-starter. >> > > I am worried you are accusing me of something Bad (TM) I did not actually > proposed. > > I said, ones cannot used .toJSON because you need to read it back, so you > should serialize / deserialize by some protocol, for which you need to > supply the transforming functions, JSON.parse as well as JSON.stringify > have extra parameters for them Of course, but again, I'm not sure how either of those would help identify which: '{ "foo": [1,2,3,4,5], "bar": [1,2,3,4,5] }' ...Is the Array and which is the Set Maybe I'm still misunderstanding? If I am, I apologize > (plus contemplated the idea that such composable wrappers/unwrappers for > Sets, Maps etc. could be supplied because they can be handy, but probably > library is the better level for this than the language). +1, this is something library authors should tackle before any language attention is given. Rick > > > Rick >> >> Introducing another Set constructor just to wrap the above is >> early-warning feature creep. toJSON is an intuitive addition >> > > Definitely not "feature-creep another Set constructor". > > >> Rick >> >> >> Herby >> >
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