ChucK/Patterns/ExternalDataLoader

From CSWiki

I have been experimenting with a pattern for loading external data, such that once the data is loaded into the ChucK VM, an event is triggered and a consumer of the data is informed that the data is ready for loadinginng. The code below is just scratch code that I am in the process of cleaning up. When this page is complete, I will have 4 distinct modules: a DataLoadedEvent class, a data producer, a data consumer, a class to hold globally accessible static fields like the DataLoadedEvent, and a class to hold externally loaded data (class will provide nice methods to iterate over the data loaded (without having to know the specifics of the data collection)

public class DataObj {
	int mydata[];
}

public class TheEvent extends Event
{
    int value;
}

//GlobalSpace - All public class that holds globally accessible 
// Objects (in this case a user defined event class
//However you cannot (in v. 1.2.1.1) use a straightforward
//approach to capturing non-primative types in a static variable
//So we do a bare declare of e...

public class GlobalSpace {
    static TheEvent @ e;
    //static int data[200];
    static DataObj  @ callback;	
	
}
// ...then use the following to do the assignment

new TheEvent @=> GlobalSpace.e;
//This seems to be a necessary hack to allow us to 
//use a non-primitive in a static variable space 
//

// Event class is defined in the_event.ck
// and the reference to the event class is held in the GlobalSpace
// as a static variable
int data_ready;
int count;
DataObj @ dataObj;
// handler
fun int hi( TheEvent e )
{
    while( true )
    {
        // wait on event
        e => now;
        // get the data
        <<<"Data Is Ready">>>;
        1 => data_ready;
	0 => count;
	GlobalSpace.callback @=> dataObj;
    }
}

// spork
<<<"Event Receiver">>>;
spork ~ hi( GlobalSpace.e );
spork ~ hi( GlobalSpace.e );
spork ~ hi( GlobalSpace.e );
spork ~ hi( GlobalSpace.e );

// infinite time loop
/**************/
while( true )
{
    // advance time
    1::second => now;
    if (data_ready) {
	if (count <  dataObj.mydata.cap()) {
		<<< dataObj.mydata[count]>>>;
		1 +=> count;
	} else {
		0 => data_ready => count;
		
	}
    }

}
/*  */

// the event
TheEvent @ e;
GlobalSpace.e @=> e;


<<<"Flag data is ready">>>;
DataObj dataObj;
[1,2,3,5,7,11,13] @=> dataObj.mydata;
dataObj @=> GlobalSpace.callback;
e.signal();

Michael Nardell