[chuck-users] Intraspection - an example of what I'm attempting

[Andrew Turley]

Hey Rich,

You can work around the problem by casting ug[0] as a Chorus object like this:
  0.0 => (ug[0] $ Chorus).mix;
Casts are ugly, but they'll almost get the example working. The other
thing you need to do is change the line
  UGen @ ug[];
to
  UGen @ ug[0];
I'm a little rusty on the syntax, but I think what you're doing in
your code is declaring a reference to an array of references to UGens,
when what you want is an array of references to an array of UGens. If
you make the change then you get the array of references. You can then
begin to fill the array using the "array << item" syntax, which adds
elements to the end of the array. So to add the UGens to the array
you'll end up with lines like this:
  ug << chorus;
  ug << reverb;

// BEGIN CODE
SinOsc s => Chorus chorus => JCRev reverb => dac;
880.0 => s.freq;
.2 => s.gain;
UGen @ ug[0];
ug << chorus;
ug << reverb;
0.0 => (ug[0] $ Chorus).mix;

while (true) {
1::second => now;
} // main loop
// END CODE

And once you've done all this you still have your original problem,
which is that you want to be able to create an array of objects that
all respond to "mix" (or some other method) and treat them the same
way. Unfortunately there isn't a built-in way to do this. Chuck is
strongly-typed, so you can't call a method unless the object is known
to support the method. Chuck doesn't have an introspection system so
you can't ask an object what methods it supports. And Chuck doesn't
have multiple inheritance (nor does it have interfaces) so there isn't
a "MixableUGen" interface that you could use to indicated that all the
UGens in the array support the "mix" method.

You can create your own classes that have references to the UGens and
wrap up the functionality you need, so that you can call the "mix"
method an an object and it will know what to do with its associated
UGen.

andy

On Sun, Nov 7, 2010 at 6:45 PM, Rich Caloggero <rjc at mit.edu> wrote:
> Whan I run the following code, I get an error at line 7 - class UGen has no
> member 'mix'.
> How do I do this type of thing in chuck?
>
>
> // code
> SinOsc s => Chorus chorus => JCRev reverb => dac;
> 880.0 => s.freq;
> .2 => s.gain;
> UGen @ ug[];
> chorus @=> ug[0];
> reverb @=> ug[1];
> 0.0 => ug[0].mix;
>
> while (true) {
> 1::second => now;
> } // main loop
>
> ----- Original Message ----- From: "Rich Caloggero" <rjc at MIT.EDU>
> To: "ChucK Users Mailing List" <chuck-users at lists.cs.princeton.edu>
> Sent: Sunday, November 07, 2010 1:11 PM
> Subject: [chuck-users] Intraspection?
>
>
>> I want to find some way of controlling various parameters via the
>> keyboard. The problem I'm having is that in order to write some sort of
>> generic class that can change arbitrary UGen parameters (or really
>> anything), one needs to know what types your dealing with. Is there a way of
>> asking chuck what things are?
>> For instance, I can maintain some sort of list of UGens I want to control
>> via an array of UGens, but then when I attempt to access a parameter on one
>> of the objects in that array, it tells me there is no such member in class
>> UGen. THe idea is that the array would contain references to various UGens I
>> want to manipulate, and they may be of any UGen subtype. However, in order
>> to access any members, the compiler needs to know exactly which type each
>> object is.
>>
>> Any ideas?
>>
>> -- Rich
>>
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