October 2009 - chuck-users - lists.cs.princeton.edu

forward reference oddity
by Robert Poor 02 Oct '09

02 Oct '09

Here's another oddity. The following file: --------------------------------------- // file: ouroboros.ck class Ouro { Boros @ boros; fun void set_boros(Boros boros) { <<< this.toString(), "set_boros(", boros.toString(), ")" >>>; boros @=> this.boros; } } class Boros { Ouro @ ouro; fun void set_ouro(Ouro ouro) { <<< this.toString(), "set_ouro(", ouro.toString(), ")" >>>; ouro @=> this.ouro; } } --------------------------------------- gets a compile-time error: --------------------------------------- r% chuck ouroboros.ck [ouroboros.ck]:line(5): class 'Boros' has no member 'toString' [ouroboros.ck]: ...in function 'set_boros' --------------------------------------- This is odd, since (AFAIK) toString() is defined on the Object class, and all classes inherit from Object. If I remove the toString() call on boros as below, it compiles without error. Note chat ChucK has no problem compiling ouro.toString() in function 'set_ouro': --------------------------------------- // file: ouroboros.ck class Ouro { Boros @ boros; fun void set_boros(Boros boros) { <<< this.toString(), "set_boros(", boros, ")" >>>; boros @=> this.boros; } } class Boros { Ouro @ ouro; fun void set_ouro(Ouro ouro) { <<< this.toString(), "set_ouro(", ouro.toString(), ")" >>>; ouro @=> this.ouro; } } --------------------------------------- Is this because Boros is a forward reference? And is this not a bug? - Rob

3 5

The ChucK Show on iTunes
by Les Hall 02 Oct '09

02 Oct '09

Fellow ChucKists, I have great news. Unless I'm mistaken, this news is so exciting I don't really believe it's true. Shane Morris of www.electro-music.com just told me that iTunes is going to list the internet radio station that airs The ChucK Show in it's (arguably huge) list of stations! Wow, I'm excited about this. I don't know what to think, other than I should just "Keep on ChucKin'". Tomorrow at 7pm EST will be "The Game Show" which will have a lot of ChucK music on it. It's sort of a cross between the classic shows "Name That Tune" and "The Gong Show". I will play a variety of music, all from electro-music.com members, and then people in the chatroom will try to guess the author, song name, software or hardware used to create the music, etc. Multiple points are awarded each song as people guess different stuff. And my friend Bill will mail out a CD to the winner. A good time is practically a guarantee, so tune in if you can. Again, I'm not quite sure if this is real but I think it is so if you'd like your ChucK music to appear on iTunes, send me mp3's or code. Actually send both! mp3's are better if you use much CPU at all because all I have a little 5 year old eMac and it's busy running the show controller as well. See you on the radio, Les For those about to ChucK, we salute you! - Ge Wang

2 1

class abuse
by Robert Poor 01 Oct '09

01 Oct '09

I can hardly call this a bug, since people who go around casting classes get what they deserve, but it's unexpected behavior nonetheless. Consider the following -- the salient point is that General is a super class, Specific extends General. =================== class General { fun void announce() { <<< "I am general:", this.toString() >>>; } } class Specific extends General { fun void announce() { <<< "I am specific:", this.toString() >>>; } } fun General create(int type) { // factory method return (type==0)?(new General):((new Specific) $ General); } fun void process(General obj) { <<< "processing general object:", obj.toString() >>>; } fun void process(Specific obj) { <<< "processing specific object:", obj.toString() >>>; } General @ obj; create(0) @=> obj; // [1] create a General object obj.announce(); // [2] calls General.announce() process(obj); // [3] calls process(General obj) create(1) @=> obj; // [4] create a Specific object obj.announce(); // [5] calls Specific.announce() process(obj); // [6] calls process(General obj) process(obj $ Specific); // [7] calls process(General obj) =================== which produces the following (I've annotated the line numbers): =================== r% chuck classtest.ck [2] I am general: General:5df960 [3] processing general object: General:5df960 [5] I am specific: Specific:5de400 [6] processing general object: Specific:5de400 [7] processing general object: Specific:5de400 =================== Lines [1], [2], [3] do what you expect: creates a general object, calls the General.announce() method, and calls the process() function which has the <General obj> signature. So far so good. Lines [4], [5] also do what's expected: creates a Specific object and calls the Specific.announce() method. Line [6] is up for grabs. I half expected it to call the version of process() with the <Specific obj> signature (since it called the Specific.announce() method at step [5]). On the other hand, obj was declared as a General class, so it doesn't surprise me that it called the version of process() with the <General obj> signature. Line [7] is what bugs me: obj is cast to the Specific class, and the ChucK compiler _knows_ this at compile time. Yet it calls the process(General obj) function, NOT the process(Specific obj) function. If ChucK uses run-time checking for signature discrimination, then [6] should call process(Specific obj). But it uses compile time checking, right? So why doesn't it call process(Specific obj) in step [7]? I promise not to lose too much sleep over this. If someone familiar with ChucK's type system wants to report this as a bug, be my guest. I'm just happy to find that ChucK has a smidgen of run-time type discrimination (as evidenced at [5]). - Rob

6 8

watchdog activate!
by Andrew C. Smith 01 Oct '09

01 Oct '09

[chuck]:(3:SEVERE): real-time watchdog counter-measure activating... What does that mean? How can I fix it? The shell/--loop prints it (and then stops working) fairly often, usually when I hit lots of notes really fast. Andrew

2 2

object / class hacking
by Robert Poor 01 Oct '09

01 Oct '09

Chucksters: Three questions in one message (generally a bad idea, but they're short): [1] Accessing class name from an object I seem to recall seeing a way to get an object to yield its class name, if only for printing. But I haven't been able to locate the e- mail thread where that was discussed. Was I hallucinating? (I really only want this for debugging, but if it's a supported function, it may be useful for dispatching on class type.) [2] initializing an object Is there a subclassable method that is called when you instantiate an object? or do have to instantiate then initialize manually, as in: public class Foo { Controller @ c; fun void init(Controller c) { c @=> this.c } } Foo foo; foo.init(x); [3] "natural" sorting of objects Is there any attribute of an object that you can reliably use as a sort key? I ask because I want to speed up searching of an array of objects (e.g. to see if an object is already present). As I understand it, I can't use a hash array since there are no iterators. I guess the question should be: what's the fastest way to maintain a *set* of objects (i.e. a collection in which an object may only appear once) with the usual operations for insertion, deletion and iteration? TIA. - rob

6 18

new versions?
by Fernando Lopez-Lezcano 01 Oct '09

01 Oct '09

I realize that no new big things may have changed at the source level that would trigger a new release of chuck and, say, miniaudicle. But. Isn't it time to do it anyway? Anyone downloading and trying to compile either package from source in a modern up to date linux distro will find that the software does not build. Not a good first time experience. Chuck should move with the times, including patching it for stricter (current) gcc releases, etc, etc. IMHO, of course. -- Fernando

4 3