[chuck-users] zipper noise (++)
gewang at CS.Princeton.EDU
Fri May 5 00:36:57 EDT 2006
Hi Kassen and all!
> "need" is a big word but if you would have a moment to spare I would
> very much apreceate your thoughts on some of the issues around those
> asignments of ugen's to array members.
The current specification for arrays of Objects is that each element is a
reference, like a non-array Object variable, can be treated as such.
For example, as you know:
Object @ bar;
At this point, both foo and bar is a reference variable to an Object, the
only different being foo is referencing an instance of Object, whereas bar
is referencing NULL at this point.
// assign foo to bar: both now point to the same instance
foo @=> bar;
Going to arrays isn't really any different:
Object @ barray;
fooray simply contains 10 references (each referencing at this point to
newly allocated Object instances), barray also contains 10 references, but
due to the @ declaration all elements are NULL. Except for this
difference, fooray and barray are the same: they both contain references
If we want, we can assign references to the elements of fooray and barray:
// assuming fooray.cap() == barray.cap()
for( int i; i < fooray.cap(); i++ )
fooray[i] @=> barray[i];
This above fills barray's elements with corresponding elements of fooray.
We can also assign new instances to fooray's elements and to barray's
// make a new Object (reference variable obj)
obj @=> fooray;
obj @=> barray;
// make a new Object
new Object @=> fooray;
new Object @=> barray;
The objects, in theory, are reference counted and garbage collected as
appropriate. In practice, the garbage collection system is not finished
(completing it is actually the main goal, along with string manipulations,
of the 220.127.116.11 release). In the cases above, it actually works, I think.
In the case of UGens, it's no different really, except the @=> and =>
operators do completely different things. As Perry explained:
foo => bar; // connects foo to bar, as we all know
foo @=> bar; // assigns foo to bar
In the 'foo @=> bar;' case, bar now references the same UGen as foo.
What bar was previously referencing should have it's reference count
decremented and be potentially garbaged collected.
Things get potentially kind of wacky is when we combine @=> and => into a
single statement, like:
// make an array (all elements == NULL, due to @)
sinosc @ bank[N];
// make new sinosc, assign it to bank, connect it to dac
sinosc s @=> bank => dac;
Like Perry wrote, this decomposes into the following lines:
// make new sinosc
// assign it
s @=> bank;
// connect bank to dac
bank => dac;
The thing to remember is @=> always signifies assignment, => depends on
And that's pretty much it. I am actually still not sure if I answered the
right question - please let me know... Doh. If this part of the language
seems confusing, we can certainly try to improve it.
Best wishes, Kassen and all.
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