[Bug 19803] "Fingerprint" is unclear

https://www.w3.org/Bugs/Public/show_bug.cgi?id=19803

--- Comment #15 from Jussi Kalliokoski <jussi.kalliokoski@gmail.com> ---
(In reply to comment #14)
> Hmm, yes.  Would have to see what happens with device IDs when doing the
> unplugging dance.  I don't have a Windows instance handy or I'd test.

Ahh, I just tried it, and of course, I'd forgotten about this! On Windows, you
can only have one handle per port, trying to get another will give you an
error, so once you do a midiInOpen(), your HMIDIIN handle becomes an exclusive
access to that device. What a PITA, but at least it makes my algorithm work on
Windows.

> Well, we don't currently have a way to do that; I don't think we should be
> saying that we'll return the same MIDIInput *instance*, for example, or
> people are going to step on their own onmessage handlers.  Or we need to
> explicitly say that.  Actually, we probably should explicitly say that
> either way.  Does that make sense?

Oh nono, that's exactly what the fingerprint does, it allows you to see if two
port instances are referring to the same port. But yes, equality between two
instances of the port might have ugly consequences, and is not a good idea.

> If we do make MIDIPorts have singular instances, I should point out that we
> would NOT be able to make the equality work across Worker boundaries, if we
> take that on.  Not sure it really matters.

I think it's best that equality is measured by comparing the fingerprints
rather than instances in this case.

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Received on Sunday, 9 December 2012 11:01:34 UTC