http://www.santafe.edu/projects/swarm/archive/list-archive.9904/0119.html

/*
The two main points are:
1) Use of addRef:withArgument: and notifyFunction
2) Conservative use of remove: in notifyFunction

[apologies to Stevie Wonder]
*/
#import <simtools.h>
#import <activity.h>
#import <objectbase/SwarmObject.h>

@interface TargetObject: SwarmObject
- printTime;
@end

@implementation TargetObject
- printTime
{
printf (">TargetObject@%lu\n", getCurrentTime ());
return self;
}
@end

@interface Controller: SwarmObject
{
id <Schedule> schedule;
id targetObject;
}
+ createBegin: aZone;
- (id <Schedule>)getSchedule;
- scheduleStuff;
- (void)dropTarget;
- ponderTheUniverse;
- go;
@end

static void
notifyFunction (id obj, id unused, void *arg)
{
id controller = (id) arg;
id <Schedule> schedule = [controller getSchedule];
id action;

do {
id <MapIndex> index = [schedule begin: scratchZone];

while ((action = [index next]))
{
if ((timeval_t) [index getKey] > getCurrentTime ())
{
if ([action respondsTo: M(getTarget)])
if (obj == [action getTarget])
{
printf (">Removal of ActionTo@%lu! (target=%s)\n",
(timeval_t) [index getKey],
[[action getTarget] name]);
[schedule remove: action];
break;
}
}
}
[index drop];
} while (action);
}

@implementation Controller
+ createBegin: aZone
{
Controller *obj = [super createBegin: aZone];

obj->targetObject = [TargetObject create: aZone];
[obj->targetObject addRef: notifyFunction withArgument: obj];

return obj;
}

- scheduleStuff
{
schedule = [Schedule create: globalZone];

[schedule at: 0 createActionTo: targetObject message: M(printTime)];
[schedule at: 1 createActionTo: self message: M(dropTarget)];
[schedule at: 2 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 3 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 4 createActionTo: targetObject message: M(printTime)];
[schedule at: 5 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 6 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 7 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 8 createActionTo: self message: M(ponderTheUniverse)];
[schedule at: 9 createActionTo: self message: M(ponderTheUniverse)];
return self;
}

- ponderTheUniverse
{
timeval_t t = getCurrentTime ();
const char *strs[] = {
"<oink>",
"<frob>",
"\nVery superstitious, wash your face and hands",
"Rid me of the problem, do all that you can",
"<snort>",
"Keep me in a daydream, keep me goin' strong",
"You don't wanna save me, sad is my song",
"\nWhen you believe in things that you don't understand",
"Then you suffer",
"Superstition ain't the way"
};
printf ("%s\n", strs[t]);
}

- (id <Schedule>)getSchedule
{
return schedule;
}

- (void)dropTarget
{
[targetObject drop];
}

- go
{
return [[schedule activateIn: nil] run];
}
@end

int 
main (int argc, const char **argv)
{
id controller;

initSwarmBatch (argc, argv);

controller = [Controller create: globalZone];

[controller scheduleStuff];
[controller go];

return 0;
}

/*
Local Variables:
compile-command: "/opt/egcs/bin/gcc -o s -g -Wno-import -L/opt/SUNWtcl/8.0/sun4/lib -R/opt/SUNWtcl/8.0/sun4/lib
-L/opt/SDGblt/2.4g/lib -R/opt/SDGblt/2.4g/lib -L/opt/SDGlibffi/1.20/lib -R/opt/SDGlibffi/1.20/lib
-L/opt/SDGswarm/1.4.1/lib -L/opt/SDGzlib/1.1.3/lib -L/usr/local/X11/lib -R/usr/local/X11/lib -L/usr/openwin/lib
-R/usr/openwin/lib -L/opt/SDGhdf5/1.0.1/lib -I/opt/SDGswarm/1.4.1/include s.m -lanalysis -lsimtools -lsimtoolsgui
-lactivity -ltkobjc -lrandom -lobjectbase -ldefobj -lcollections -lmisc -ltclobjc -ltk8.0 -ltcl8.0 -lBLT -lsocket -ldl -lnsl
-L/usr/openwin/lib -lhdf5 -lpng -lz -lXpm -lX11 -lffi -lm -lobjc -lpthread -lposix4"
End:
*/