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：

public Object buildActions () {
& L) x! ~8 t0 ]7 L5 S. }: `. N1 E    super.buildActions();
   
    // Create the list of simulation actions. We put these in
. z2 [* N# a) G: e    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
$ c4 x/ F8 b8 W% y( N0 r" g$ }8 r    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
' E6 a! I8 t  D! K  O; H        
    // Note we update the heatspace in two phases: first run
: o1 u/ ]5 {& i4 d$ F0 @. V    // diffusion, then run "updateWorld" to actually enact the
+ p$ }' i& T) }2 ]    // changes the heatbugs have made. The ordering here is
    // significant!
        
3 P; i1 t! t% k. t. U    // Note also, that with the additional
6 N% v  O) R, n    // `randomizeHeatbugUpdateOrder' Boolean flag we can
1 {2 w4 Z  _, ~2 c    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
8 c9 [6 q4 h# d5 \0 _, x0 j: R    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
8 m5 Q$ @% b( A- u0 A" N, a        
    // By default, all `createActionForEach' modelActions have
    // 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
    // indirectly by some other process).
   
% }0 @% k! b1 s8 o0 z: `  }6 r    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
$ N+ U5 E4 _. c8 A. k    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
" K$ l  p" @  R5 w  F5 N    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
% ^2 x0 M# Q4 N. ]2 H9 [( ^# Z7 {      actionForEach =
  q; \4 M6 v( u# R        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
4 a/ r0 ~# z( r3 Q+ }* q         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
  o) s3 {9 n/ w5 F# A- F5 _      e.printStackTrace (System.err);
7 |. l8 g) M& H+ r6 E8 ?, M    }
8 q% Y0 K( p: g* }9 H) V/ S$ t   
    syncUpdateOrder ();

6 P. Z; k. y' i8 S# {! r' b6 t& B1 t    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
6 Q) O* ~2 @6 u' X8 |    }
  x; T* x1 e7 H; w$ f        
    // Then we create a schedule that executes the
2 _: }8 `& W2 I% [5 U    // modelActions. modelActions is an ActionGroup, by itself it
- U& B  r3 u" f! I8 j& G' J6 {    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
8 }/ H7 z  a& \& Z. S    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
: @% L3 A' P( v; g8 Y2 L+ y/ l
$ Q: N5 _- C" K    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
6 f( S/ B, W& F# x, T) \' W$ y8 t    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }