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：

  Z. X$ I# A: L% Y% t" R9 f public Object buildActions () {
( T( c. F" w' M8 z5 _% u' X& [    super.buildActions();
   
    // Create the list of simulation actions. We put these in
% n* Z2 T" N5 G    // an action group, because we want these actions to be
' L- B- D% g% a, `0 R    // executed in a specific order, but these steps should
8 C1 t8 q! v9 {    // take no (simulated) time. The M(foo) means "The message
! s& X9 F0 Z+ y4 |6 b    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
: b. p0 T! m: t/ P2 @; V+ r/ T- T        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
, |0 m5 b4 f/ e$ Z$ ~    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
' O4 O6 d: b$ s0 I: h, f$ w9 O    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
: q4 v$ r9 }# v6 @    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
9 z# j0 r% f! g, Z8 J  e% Q        
    // By default, all `createActionForEach' modelActions have
3 ^1 }9 `* C  B: X7 j) r' \    // 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).
$ f- X2 z+ l; s% }   
1 u& s4 E# \. m" r9 e& y    modelActions = new ActionGroupImpl (getZone ());

: ]% \9 I+ Z- N1 f8 p! M, [0 |; D7 |    try {
" \; |- R. E$ U1 z9 n      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
3 m1 q; e8 Z6 H/ \; Y) H& d% b      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
" o! T6 y; e3 X6 g
    try {
3 r8 y$ L$ T# B* S' z& w      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
. a% m) P# L# e        new Selector (proto.getClass (), "heatbugStep", false);
6 a5 j( `- x4 b! N+ T      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
) \/ f: i) i, m4 F, I6 T6 L; o
    try {
5 W: v4 R- v- @% j6 Y      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
+ [( }2 l3 ~4 J2 c7 C. q) O2 c    } catch (Exception e) {
0 h! o0 ]* D! L" `' N: V& Y. S+ A      System.err.println("Exception updateLattice: " + e.getMessage ());
) Z" U! i+ r" D8 B7 K    }
        
: D& H# G9 Q9 Z( F, ?' G1 ?' N( {+ r8 M    // 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
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
5 @' |4 ~6 k- D( }    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
9 o* t* H8 y* m* G6 @    // the beginning of the loop.
; ]7 I: a! @  U
7 ^/ l$ [' Q( g5 e: x; a# S& E( @    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
, Z* o8 o; J0 X3 _& o  w6 `    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
6 J1 R# H' b% P" U& q        
6 r2 Q. c" x2 S# P7 {- ^    return this;
4 R# |7 `, k; c  }