问jheatbugs-2001-03-28中某些代码

sybbk

HeatbugModelSwarm中buildActions部分，3个try分别是做什么？查了下refbook-java-2.2，解释太简略，还是不懂，高手指点，谢谢！代码如下：

! I) n4 |, P& L' d4 `3 A public Object buildActions () {
. {, f$ a+ m2 H& t4 B# v    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
$ Q" }# ^2 B: [0 K1 l3 {; Z    // take no (simulated) time. The M(foo) means "The message
3 a) g4 X+ l3 [    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
& ^! v- W+ H' {        
$ [$ P, B" p6 I) R2 Z3 y( D& L: t    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
6 C7 m9 Q; p+ h: x! t/ s    // changes the heatbugs have made. The ordering here is
  W) q4 @" @  _! C, a$ V% W    // significant!
        
1 a3 `% x) E" b0 d  e: Q) l    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
% k/ Q; P' ]7 u; `: ?  x' d    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
3 {- c8 O8 h: R9 H& O4 o    // list from timestep to timestep
        
& E% f1 {6 [% p& ?$ @" b2 o) E# i    // By default, all `createActionForEach' modelActions have
8 y8 x3 N0 G$ I4 Q1 E0 B    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
8 s8 F( Z" h3 Q    // indirectly by some other process).
% u1 O8 I3 N) _  J( J3 O5 ?7 H: A   
/ D8 G4 Y9 @5 S3 Q* p: m    modelActions = new ActionGroupImpl (getZone ());

    try {
) M; E2 ~3 G: n# O      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
7 K% F% O5 _, C  ?# Q' Y% x      System.err.println ("Exception stepRule: " + e.getMessage ());
# o8 U6 ^1 G$ v2 i) W/ D6 I3 y    }

/ X  [. L" p" ]1 r+ W6 U3 V1 d, ~" C    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
0 V1 x$ H$ s5 q0 f      Selector sel =
1 @9 v. y' i4 G8 Z2 ~$ _        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
: j  v5 `9 y5 v. q      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
3 p# z& {3 h: L* K7 `8 ~
. w/ i) e0 S. o9 L3 s3 V/ j7 Q5 S6 k& S    try {
      modelActions.createActionTo$message
% G. n. ]5 m) ?. A        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
4 _9 P% x, B$ n    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
# q/ I. k1 g) D; A7 R    // has no notion of time. In order to have it executed in
- n- L; F" [0 x) A8 r; }  p) L+ B4 a* ?    // time, we create a Schedule that says to use the
  P2 i3 U7 F* \7 G    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
3 k5 o4 `* o1 U5 d6 G0 N    // time step.  The action is executed at time 0 relative to
) ]9 [5 f9 B9 |' n    // the beginning of the loop.
0 s: [0 [+ r2 ]1 l: T
    // This is a simple schedule, with only one action that is
' {5 F! I* c! h- S' z9 }    // just repeated every time. See jmousetrap for more
3 a  f0 d: V2 i9 C  _    // complicated schedules.
1 A) Q7 ^! q8 P( h9 u  
  |2 {0 P" w& V2 w! [6 M    modelSchedule = new ScheduleImpl (getZone (), 1);
4 ?: ?6 @8 p( z7 f: K4 q0 q: i1 h    modelSchedule.at$createAction (0, modelActions);
        
* m# Q/ w$ c3 ]1 L    return this;
+ e3 Z- Q; N* u7 @  }