[PD] How does vline~ work under the hood?

[i go bananas]

I actually think Frank might have the my answer here.

What i'm noticing, is not an inconsistency in the length of the ramps.
It's an inconsisency in when they are first triggered.  This is for stuff
like the initial click of a bassdrum, so you can even hear the difference
quite clearly.  The line object jumps around, as it is being triggered on
block boundaries, but the vline object is faithfully consistent in starting
at the exact TIME i ask it to - regardless of blocksize, etc.

The only logical answer i can see here, is the one Frank has given.  I'm
scheduling drums using a clock controlled by metro.

So what i'm guessing that Frank is suggesting here, is that the scheduler
is keeping a list of all the metro and delay bangs that should arrive in
the upcoming block, and sceduling them to be hit while the block plays.
And what vline does, is it reads that list, and then schedules itself to be
hit after the correct amount of logical time has elapsed.

And i would guess that the normal line object is not capable of that.  It
just waits until block boundaries and starts its simple incrementation.

So, going back to Jonathan's day-long block example, i can see now how that
works.  the line can only be triggered once, at the start of the block (i
still have doubts that it would actually stretch to the length of the block
though.  I reckon a 50ms line is still gonna take 50ms. )
But the vline has that linked list inbuilt, and it reads from the scheduler
to see when it should be triggered.  So if you had the day-long block, then
vline's linked list is gonna end up with a full day's worth of messages in
it!

Anyway, i'll go back to the source code tomorrow and have another look.
But pretty sure that i now see how it is the ability to look ahead at metro
scheduled events that gives vline the accuracy i need.

Thanks Matt for suggesting i look at the clock, and scheduler code, thanks
Jonothan for the great example of the day long block - taking things to
extremes like that is a good way to see how they work.  And thanks Frank
for finally turning on that lightbulb and suggesting the role that metro
was playing here.
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