I think using WeakMaps is a good idea. Using a Symbol will keep from cluttering the namespace with names others might want to use (id,label,etc) and seems more consistent than some external means of accessing the id. When I tried defining the value before I ran into issues with the prototype chain which is why I was using get and a second 'hidden' property. Using WeakMap seems like it'd fix the issue.
Can't say I've used Object.assign much - will have to experiment with it. Thanks, Michael McGlothlin Sent from my iPhone > On Sep 9, 2015, at 7:34 AM, Andrea Giammarchi <[email protected]> > wrote: > > Well, to start with, you don't hide symbols, these are all exposed through > `Object.getOwnPropertySymbols` or Reflect.ownKeys so for your use case looks > like using just a non enumerable property would do as well. > And btw, even if Symbols don't show up in for/in and Object.keys, these are > by default also enumerable so Object.assign will copy them around (reason > I've used defineProperty with the value instead of just setting the symbol, > so it's non enumerable by default). > > As summary: do you want to be sure that object has a unique "lable" or "id" > associated with it? Use WeakMaps, otherwise be prepared to possible clones > around if some library uses Object.assign thinking that's a good way to copy > properties around. > > I still suggest the Labeler approach that Mark previously indicated. > > Regards > > > > >> On Wed, Sep 9, 2015 at 1:15 PM, Michael McGlothlin >> <[email protected]> wrote: >> Using frozen objects and such seems a lot more complex to me than just using >> a property. Using a symbol to hide the property from cluttering seems to go >> along with how other things are being done. And it's my understanding that >> other than hiding it that using a Symbol for a name is nothing special - >> does it have some negative factor that should make using it less attractive? >> >> 📱 Michael McGlothlin >> >>> On Sep 9, 2015, at 5:36 AM, Andrea Giammarchi <[email protected]> >>> wrote: >>> >>> That's similar to the Labeler proposed by Mark, except it needs to search >>> for the thing twice (wm.has + wm.get instead of just wm.get which would be >>> just fine as check if you count from 1 instead of 0 ;-) ) >>> >>> Although I need to understand if you have a wm why wouldn't you just use >>> that instead of a Symbol ... so the Labeler seems again a more appropriate >>> pattern for this problem. >>> >>> Just my thoughts >>> >>>> On Wed, Sep 9, 2015 at 10:51 AM, Michał Wadas <[email protected]> >>>> wrote: >>>> Following solution will work: >>>> >>>> (function(){ >>>> const wm = new WeakMap(); >>>> Symbol.identity = Symbol( 'Symbol.identity' ); >>>> let i = 0; >>>> Object.defineProperty( >>>> Object.prototype, >>>> Symbol.identity, >>>> { >>>> get: function () { >>>> if (wm.has(this)) return wm.get(this); >>>> wm.set(this, Symbol(i++)); >>>> return wm.get(this); >>>> } >>>> } >>>> ); >>>> })() >>>> >>>> >>>> 2015-09-08 23:29 GMT+02:00 Andrea Giammarchi <[email protected]>: >>>>> as side note, that's just a lazy assignment that doesn't need two symbols >>>>> and a constant get invoke ... >>>>> >>>>> ```js >>>>> Symbol.identity = Symbol( 'Symbol.identity' ); >>>>> var OBJECT_ID = 0; >>>>> Object.defineProperty( >>>>> Object.prototype, >>>>> Symbol.identity, >>>>> { >>>>> get: function () { >>>>> // first time this is invoked ... and no more ... >>>>> Object.defineProperty(this, Symbol.identity, {value: ++OBJECT_ID}); >>>>> // from now own, direct property access \m/ >>>>> return this[Symbol.identity]; >>>>> } >>>>> } >>>>> ); >>>>> ``` >>>>> >>>>> Regards >>>>> >>>>>> On Tue, Sep 8, 2015 at 9:57 PM, Michael McGlothlin >>>>>> <[email protected]> wrote: >>>>>> I try to keep it pretty simple. It's not fancy but the times you want >>>>>> fast and dirty information like this are the same times you don't want >>>>>> to have to define it manually. >>>>>> >>>>>> Symbol.identity = Symbol( 'Symbol.identity' ); >>>>>> const identity = Symbol( 'identity' ); >>>>>> var OBJECT_ID = 0; >>>>>> Object.defineProperty( Object.prototype, Symbol.identity, { >>>>>> get: () => { >>>>>> if ( !Object.hasOwnProperty.call( this, identity ) ) { >>>>>> this[ identity ] = ++OBJECT_ID; >>>>>> } >>>>>> return this[ identity ]; >>>>>> } >>>>>> } ); >>>>>> >>>>>>> On Tue, Sep 8, 2015 at 1:44 PM, Mark S. Miller <[email protected]> >>>>>>> wrote: >>>>>>> See Labeler at >>>>>>> http://wiki.ecmascript.org/doku.php?id=harmony:weak_maps#unique_labeler >>>>>>> >>>>>>> >>>>>>> >>>>>>>> On Tue, Sep 8, 2015 at 11:16 AM, joe <[email protected]> wrote: >>>>>>>> Didn't send to list, something is wrong with my reply all. Sorry about >>>>>>>> that. Stupid mobile gmail. >>>>>>>> >>>>>>>> ---------- Forwarded message ---------- >>>>>>>> From: "joe" <[email protected]> >>>>>>>> Date: Sep 8, 2015 11:15 AM >>>>>>>> Subject: Re: Object id, hash, etc? >>>>>>>> To: "Garrett Smith" <[email protected]> >>>>>>>> Cc: >>>>>>>> >>>>>>>> I agree with this request. This is the logical complement to valueof, >>>>>>>> I think. And yes, for most ID use cases this isn't a good fit, but >>>>>>>> we're not talking about the general case, just the cases where a >>>>>>>> python style id() function *is* appropriate. >>>>>>>> >>>>>>>> Joe >>>>>>>> >>>>>>>>> On Sep 8, 2015 9:08 AM, "Garrett Smith" <[email protected]> >>>>>>>>> wrote: >>>>>>>>> On 9/8/15, Michael McGlothlin <[email protected]> wrote: >>>>>>>>> > Is there a reason not to provide an object id and hash value as >>>>>>>>> > other >>>>>>>>> > languages often do? I find myself defining an identity symbol on >>>>>>>>> > objects >>>>>>>>> > with a value from a simple global counter. It makes it easier to >>>>>>>>> > debug if I >>>>>>>>> > can just look at a log and see what objects and functions were >>>>>>>>> > active. >>>>>>>>> > >>>>>>>>> > Likewise a hash value would simplify a lot of comparisons and make >>>>>>>>> > it easier >>>>>>>>> > to debug. >>>>>>>>> > >>>>>>>>> > I especially find the ID useful when working with bound functions >>>>>>>>> > as they >>>>>>>>> > can be difficult to tell apart. I like to change toString() to >>>>>>>>> > provide the >>>>>>>>> > ID followed by the code (flattened to one line). >>>>>>>>> > >>>>>>>>> > >>>>>>>>> >>>>>>>>> NFE's are safe to use where IE8 support isn't needed*. >>>>>>>>> (function aa(){}).name; // "aa" >>>>>>>>> >>>>>>>>> As for using Object IDs and Object Pooling, lexically-scoped values >>>>>>>>> have benefits over global ID generators (as your counter). The values >>>>>>>>> can be passed in as a parameter to the Factory (useful with Private >>>>>>>>> Proxy). There other benefits to this pattern regarding memory >>>>>>>>> management and application design. Contact me if you'd like to learn >>>>>>>>> more. >>>>>>>>> >>>>>>>>> * https://kangax.github.io/nfe/ >>>>>>>>> -- >>>>>>>>> Garrett >>>>>>>>> @xkit >>>>>>>>> ChordCycles.wordpress.com >>>>>>>>> garretts.github.io >>>>>>>>> personx.tumblr.com >>>>>>>>> _______________________________________________ >>>>>>>>> es-discuss mailing list >>>>>>>>> [email protected] >>>>>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> es-discuss mailing list >>>>>>>> [email protected] >>>>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Cheers, >>>>>>> --MarkM >>>>>>> >>>>>>> _______________________________________________ >>>>>>> es-discuss mailing list >>>>>>> [email protected] >>>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> es-discuss mailing list >>>>>> [email protected] >>>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>> >>>>> >>>>> _______________________________________________ >>>>> es-discuss mailing list >>>>> [email protected] >>>>> https://mail.mozilla.org/listinfo/es-discuss >
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