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：

( f2 E, X" N" ]5 x( H* t public Object buildActions () {
    super.buildActions();
   
9 A4 K$ Q, S' ^    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
& d7 s6 _5 ~/ M7 F$ ^% x9 e    // executed in a specific order, but these steps should
1 D3 p4 c; t: w; l/ L    // 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.
! t: D7 d. F/ t6 G        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
( U- k; b9 L, Z5 e; W7 X$ q    // changes the heatbugs have made. The ordering here is
    // significant!
3 H4 v0 R1 l# H! b* O) A  @8 l        
3 f5 x) ]$ ~1 y- M    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
( E3 q$ @: b, y+ ]8 T& M3 o    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
$ S5 @; K: ~2 _0 J% l- u    // 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).
   
    modelActions = new ActionGroupImpl (getZone ());

8 o0 I: h+ J, m" Q; l# ^. b    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
, K; c$ ~: ^- E/ N    } catch (Exception e) {
( p9 L/ w0 u6 `      System.err.println ("Exception stepRule: " + e.getMessage ());
9 |4 a6 M) e7 F" R3 d) s# ]    }

! Z7 g5 H" P4 b3 N/ I8 r5 n! N    try {
* @) ]2 n- }; ~1 q8 |" j2 Y      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
  k7 Y: v+ t% p9 q0 S* A        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
. u. `& x; e! H: F" R8 ?         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
  F# P! V( y$ _8 E. v    }
( h* A; ~. S% o   
    syncUpdateOrder ();
: f* L! b- Q4 ~- }2 j* i& ]
    try {
      modelActions.createActionTo$message
( c+ U; I) ~( o6 j1 x3 D        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
* K: N4 q, w3 ^+ x    // time, we create a Schedule that says to use the
/ n$ X9 b) |) V: z1 R/ L) H! C; P    // 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.
1 [' k- k2 \8 d( i! k
    // This is a simple schedule, with only one action that is
; a. r4 I+ J* z" f/ n    // just repeated every time. See jmousetrap for more
% x: Z* w9 S7 {    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
) N: X$ d2 S0 ?" w    modelSchedule.at$createAction (0, modelActions);
        
1 H* C7 n* e( l! r4 k6 A    return this;
; K: V9 E' V# t5 b" N2 A. ^  }