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：
7 T2 M  C$ R- p1 r
4 Y1 G' W- e' K$ M7 T7 S, J5 h public Object buildActions () {
    super.buildActions();
   
/ Y: c1 ~! _5 A, i' a, |; g+ L    // 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
1 w8 X% w+ G3 w) U) G/ I. Z    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
    // 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
; ^4 O& u9 N8 n    // changes the heatbugs have made. The ordering here is
    // significant!
7 v/ P. T  P2 p3 {: T& ^6 k        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
- Q" m- J' n. w. F    // their step rule.  This has the effect of removing any
- ~: r8 L, F9 e    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
8 n: Q8 R( C  Q    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
  y' w1 ?  N0 i& m$ d0 u    // order of iteration through the `heatbugList' will be
+ o6 g# g) T3 V) v6 ^    // identical (assuming the list order is not changed
. t; v. o) ~& i& F2 v: }    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
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    try {
) d  i: r4 K4 X8 ?      modelActions.createActionTo$message
9 y( q: G2 q9 M$ P7 s8 L) `5 \        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
4 m1 D  e  }3 x- ?) g2 g) H      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

" d. Y6 Z6 g* J  c    try {
) ?" C+ p, k  y& z0 j      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
5 M0 v. u, X1 j* V2 C0 d      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
# y; T' s( h0 Q4 S! m$ a: G$ H; c( |      e.printStackTrace (System.err);
    }
8 o2 }2 k8 o6 G7 j   
( z$ O* V1 x5 W5 T    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
, W1 ~2 U% J4 D- ^3 e    } catch (Exception e) {
  V) V# g8 n0 `1 |, E1 E( `7 ~* E) C      System.err.println("Exception updateLattice: " + e.getMessage ());
9 c6 ]: y5 h, L5 D0 F' L# ~  }    }
8 r) Y# o( n4 l' D+ j        
# h% s) B! M+ R7 J    // Then we create a schedule that executes the
* D% f7 S& [/ k# T" t% N    // modelActions. modelActions is an ActionGroup, by itself it
( H- W6 S/ w8 c) Y# ]# C0 q    // has no notion of time. In order to have it executed in
. Q1 p2 p2 y; H5 }; n/ B    // time, we create a Schedule that says to use the
/ W: o! Q8 ~+ x8 c' I! b+ g    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
# s+ S+ O" K$ ?" y2 [. K' a  Z7 J
7 h8 J3 e7 b& y. }    // This is a simple schedule, with only one action that is
, c  u7 R( V1 J8 p% H$ ^    // just repeated every time. See jmousetrap for more
1 n% c4 @% r6 X' T4 P* `* R* m5 y    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
" O9 z; {4 p9 _( R    return this;
2 o0 L9 }$ E: w* \4 T8 N  }