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：
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6 p& ~( N$ T* a. L public Object buildActions () {
    super.buildActions();
8 \7 M3 I( M- R& |6 u   
    // Create the list of simulation actions. We put these in
% O- s1 A4 q* c; n9 h2 T7 E9 ?    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
) e/ R  w6 v# Z" u0 _. w& M    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
$ k! ^1 P2 \1 c" M1 R4 C) u1 _    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
; j) e" U9 J' q    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
$ K/ I  |8 J) |6 h: R( m' O& m    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
    // list from timestep to timestep
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    // By default, all `createActionForEach' modelActions have
2 C- i; v( g! G& X    // 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
5 a4 w: B( c4 O    // indirectly by some other process).
7 j, o+ }( U* R2 g   
# w8 |" R- t; ~$ Z- i    modelActions = new ActionGroupImpl (getZone ());
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    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
; {! u" j, V: N2 }8 U( Y3 L4 W    }
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    try {
! N" S& A7 M9 L  [1 Q: i, T- L      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
9 W1 R$ T/ c1 l0 {- D& p! b      actionForEach =
3 ~. w9 L+ M& F& u+ M        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
1 \' Q% h  H& P5 h      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

* v6 u. d1 t" c' k& Y- Q    try {
      modelActions.createActionTo$message
: K% Q6 p- ]9 n        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
! A0 U& a( o5 e    }
        
    // Then we create a schedule that executes the
% P, l- K3 T! S( \" I    // modelActions. modelActions is an ActionGroup, by itself it
    // 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
+ n, e4 O, Q9 Q, K" B  G# m4 L    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
5 s3 X" [0 x8 D    // the beginning of the loop.
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    // This is a simple schedule, with only one action that is
' b6 T9 F8 S5 |    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
! |: o9 m8 F. E, Y0 D    modelSchedule = new ScheduleImpl (getZone (), 1);
/ g6 x# L* w0 i0 S0 L- A1 V1 B7 U2 B    modelSchedule.at$createAction (0, modelActions);
        
- [/ O; H- }' ^) K    return this;
  }( j; Y$ l$ J! W- L" T) V* ]  }