On Wed, Dec 4, 2013 at 8:54 AM, Mark Miller <erig...@gmail.com> wrote:
>
>
> Given a synchronous join:
>
> if (join(master, slave)) {
> ... use master for mastery stuff, use slave for slavy stuff ...
> } else {
> ... do the more expensive thing ...
> }
>
The sync case should be
if (doesJoin(master, slave)) {
... use master for mastery stuff, use slave for slavy stuff ...
} else {
... do the more expensive thing ...
}
where doesJoin is defined as
function doesJoin(x,y) {
try {
join(x,y);
return true;
} catch(_) {
return false;
}
}
IIUC, doesJoin has the properties of the equivalence relation you seek.
FWIW, this demonstrates that doesJoin is easily built from a hypothetical
sync join operation.
>
> Given the actual async join:
>
> Q(join(master, slave)).then(() => {
> ... use master for mastery stuff, use slave for slavy stuff ...
> }, () => {
> ... do the more expensive thing ...
> });
>
> We're here using join only to test whether it succeeds, not to actually
> use its result. Admittedly this is kludgy, but IMO no more kludgy than the
> problem statement demands. This would certainly not be the typical case for
> using join.
>
>
>>
>>
--
Cheers,
--MarkM
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