On Tue, 18 Feb 2025 00:53:59 GMT, Nir Lisker <nlis...@openjdk.org> wrote:
> Regarding vetoing, I noticed that only the first registered listener can veto
> since it overrides any subsequent value set.
>
> Suppose listener A changes the value to 5, B changes it to 6, C changes it to
> 7, and Z does nothing, then upon setting a value from 0 to 1 we will see:
>
> ```
> A sees 0->1; sets to 5
> A sees 1->5
> B sees 0->5; sets to 6
> A sees 5->6; sets to 5
> A sees 6->5
> C got 0->5; sets to 7
> A sees 5->7; sets to 5
> A sees 7->5
> Z sees 0->5
> ```
>
> Is this intended?
That's an interesting case. B is not notified that the value reverted to 5, as
it was already previously notified with 5 (the call would be `5 -> 5` which is
skipped). If we did however, we'd have an infinite loop which such
unconditional vetoing going on.
There can however be conditional vetoing. A case where A allows only positive
values and B allows only uneven values would run like this:
Value is set from 0 to -4.
A sees 0 -> -4; changes it to 4
A sees -4 -> 4; does nothing
B sees 0 -> 4; changes it to uneven 5
A sees 4 -> 5; does nothing
B sees 4 -> 5; does nothing
C sees 0 -> 5
I'm not sure what to think of this, and whether it needs a fix, and if so, what
that fix should be...
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PR Comment: https://git.openjdk.org/jfx/pull/1081#issuecomment-2664361246
