Aurora VS Canary Map and Set

[Andrea Giammarchi]

To summarize, Aurora is correct everywhere while Canary isn't ... and
there's nothing is specs about removing the key if the value is undefined.

I take Aurora as the right one then, thanks a lot!

On Thu, Jun 14, 2012 at 12:56 PM, Mark S. Miller <erights at google.com> wrote:

> On Thu, Jun 14, 2012 at 6:00 PM, Andrea Giammarchi
> <andrea.giammarchi at gmail.com> wrote:
> > Hi again,
> >    here few inconsistencies I have found with latest version, for Mac, of
> > these two dev/channel browsers.
> >
> > Map#set(key, value)
> >   Aurora: Map#set() returns undefined in any case. After, if value is
> > undefined/void 0, Map#has(key) will return true and Map#get(key) will
> return
> > undefined/void 0
> >   Canary: Map#set() returns the set value in any case. After, if value is
> > undefined/void 0, Map#has(key) will return false. The key will be removed
> > indeed so the get(key) will return undefined.
> >
> > My Take:
> >   returning the value with Map#set may become handier than returning
> always
> > undefined, in a JavaScript like code style.
> >   deleting implicitly the key makes no sense at all. Map has so much
> focus
> > on edge cases such NaN and +0 VS -0 but an explicit value as undefined is
> > cannot be assigned as desired value BUT it can be used as key ?!??
> Implicit
> > key removal goes against Map#delete(key) logic too since this method
> returns
> > true or false accordingly if the key was there or not.
> >
> > As Summary
> >
> > *anything value Map#set(anything key, anything value) looks the most
> > concrete/meaningful signature without implicit Map#delete(key) calls ...
> > please clarify if what I am saying makes sense and if both Aurora and
> Canary
> > will follow this behavior, thanks.
>
> I'd like to remind everyone that there's a draft spec at
> <http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets>.
> This is likely to change on the way to becoming official. But by this
> spec, the behavior you report for Aurora is correct and Canary is
> buggy. I'd appreciate it if you would file a bug report. Thanks.
>
>
> >
> >
> > Set#delete(keyAsValue)
> >   Aurora: consistent behavior with Map#delete(key) ... the returned
> value is
> > a boolean, true or false if the key was there
> >   Canary: inconsistent behavior with Map#delete(key) ...
> > Set#delete(keyAsValue) returns undefined and I really do not understand
> why
> > this is happening. My tests fails with surprise here while these where
> green
> > before ... bad choice, imho, I'd like to understand why is that.
>
> By the draft spec, again Aurora is correct and Canary is buggy.
>
> >
> > Set#add(keyAsValue)
> >   both Aurora and Canary returns undefined here and I find this a bit
> > inconsistent too. I see Set#add as a simplified Map#set where keyAsValue
> > could be returned.
>
> Returning undefined is consistent both with Aurora's behavior for
> Map#set and with the draft spec for Map#set.
>
>
> > If your argument is that Set#add(keyAsValue) has different purpose than
> > Map#set I wonder why the behavior is not consistent with Map#delete(key)
> > where at least, Set#add(keyAsValue) could return true or false
> accordingly
> > if the keyAsValue was there or not.
>
> This may be a better design -- I can make arguments both ways and we
> should have that argument. But that's the way it's currently (draft)
> speced, so for the sake of browser agreement, we should follow the
> draft spec until we agree on something else.
>
> OTOH, in alphas, betas, canarys, nightlys, or whatever prior to
> official release, it's also good to experiment with changes one is
> thinking of proposing -- in order to gain experience first. I doubt
> that is what is happening here, but if it is, we should not discourage
> it.
>
>
> >
> > if (Set#add(generic)) {
> >   // first time generic has been set
> > } else {
> >   // generic was there already
> > }
> >
> > My Take:
> >   while the returning boolean could be considered superfluous, since it
> > could be implemented in Set#delete(generic) or simply passing through the
> > Set#has(generic) check, returning the added generic value would be more
> than
> > helpful for many common tasks.
> >
> > mySingleSet.add(myGenericObject).methodCallOnAdd(/*args*/);
> >
> > Thanks for any sort of clarification.
> >
> > Best Regards,
> >     Andrea Giammarchi
> >
> > _______________________________________________
> > es-discuss mailing list
> > es-discuss at mozilla.org
> > https://mail.mozilla.org/listinfo/es-discuss
> >
>
>
>
> --
>     Cheers,
>     --MarkM
>
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