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：
* W0 g6 o* g+ P8 b+ s* x/ Q
public Object buildActions () {
) H$ h0 x3 @3 e) z! H# _$ m  D    super.buildActions();
   
) p& _" f. Q# O: r    // Create the list of simulation actions. We put these in
* E& }) i6 k9 R1 `3 ?" V    // 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
    // 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
2 \1 ~, K8 B, k: h3 ?/ B$ I" I    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
0 U+ e1 ~6 Y0 V+ u2 p/ J6 m2 O        
% l$ u3 r3 A5 b8 p: o    // Note also, that with the additional
8 F. j/ @' ^7 ^& E$ a# z9 K9 G    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
  ]7 C: z( A; h9 S0 u9 x  `    // systematic bias in the iteration throught the heatbug
+ R! d" E# K" W# q$ W    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
8 U8 _' e7 ~4 D: j! V6 S. J8 v    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
! E; ?; a" b% G2 z4 T9 q4 n$ K$ K    // identical (assuming the list order is not changed
2 ]; V) y3 v* U) H9 j    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
* E  f9 z& l0 ^
$ V! Z1 F5 z( t8 P    try {
1 `$ @/ m& z  g8 x      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
- `+ `# N$ i7 |/ j. R      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
  P7 C5 h. E8 X, }
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
8 R0 M- s1 K8 [        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
. o" B7 N' O: n1 u! x8 X5 M        modelActions.createFActionForEachHomogeneous$call
9 K/ h$ j; T4 u( |        (heatbugList,
% M. z* a; X- N$ O         new FCallImpl (this, proto, sel,
- ?/ Q6 m7 _/ t) z% X3 e                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
; r7 ]/ C- v! T& [" w; g" W; X; d    syncUpdateOrder ();

    try {
! @' p! o$ \% Z$ }8 g      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
' c7 U% [9 }) \7 h    } catch (Exception e) {
7 A4 ]! {5 }8 y% E& D3 T      System.err.println("Exception updateLattice: " + e.getMessage ());
* p8 \/ S! E9 F- b9 w; ^& o- C1 t    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
% ]9 h: _! @' e+ h    // 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
3 j3 J) K1 v/ z# ?- I& U# P    // schedule has a repeat interval of 1, it will loop every
/ u- \# l0 n9 o+ ]* ~    // time step.  The action is executed at time 0 relative to
6 ~8 L! `/ ~+ D# |8 c    // the beginning of the loop.
! c) @6 ^. _+ q" P3 `$ i0 W
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
9 m9 Q8 @+ ^( O. Q5 T  j8 b" J  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
& h6 P! F& Q6 F5 \. z1 U# N    return this;
  }