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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1 H* h- p7 u8 J* T6 ] public Object buildActions () {
1 D3 d+ x, a' z, k, Y# h    super.buildActions();
   
    // 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
+ F4 }) p! d) Z9 T2 C5 p    // 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.
7 T6 f9 ]4 F" b9 `        
    // Note we update the heatspace in two phases: first run
; P' @3 i& m) h7 R' s! v( L    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
% X: Q) J+ j, t7 L, |2 V5 P    // significant!
; ], @0 D. X. ?, }        
    // Note also, that with the additional
0 M8 d! A) T0 _' m8 e+ ?    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
5 W% L7 z' ]: O) Z5 A    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
5 ?. E8 Q% ?* T4 R) k( a# o        
    // By default, all `createActionForEach' modelActions have
2 ^' I/ Y- S* o: j) A7 y# ?    // a default order of `Sequential', which means that the
+ t3 k0 A/ q* E    // 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 ());

: a) d, X3 [+ {, L9 F* I3 L4 O    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
4 |: s& E# r6 ^% t  Y/ q8 B0 l0 H$ v    } catch (Exception e) {
. ~& l4 r. e3 z1 u- F9 ~      System.err.println ("Exception stepRule: " + e.getMessage ());
4 |$ D5 K2 L' r    }
7 G# R% `4 T" w  h/ h$ e
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
+ t7 `5 S( b# @. i* i) D      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
+ \5 ~0 A# L9 f        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
3 {* V0 u8 A, N/ ?      e.printStackTrace (System.err);
! {6 Q7 N, A0 E( A- N    }
) |# |2 y: _+ g   
) s( g8 ^! j9 }1 @/ K2 @    syncUpdateOrder ();
! K+ {- e" J$ z" q. Y
    try {
. n7 I+ e. E) [+ f! G2 G( \      modelActions.createActionTo$message
# s+ a$ e2 ~" W+ [        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
& ^% @5 D$ F5 o% R* g$ ]5 e" I2 [      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
! q# N5 e, p$ |! a. l: X) l8 X    // has no notion of time. In order to have it executed in
. b! ^6 k' F" e' n9 Z9 @    // time, we create a Schedule that says to use the
) ]+ p- D/ Z8 Z7 ^- m. T8 D    // modelActions ActionGroup at particular times.  This
. Z, I: `5 C: w( @    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
7 l) @  L, d% G' p8 ~    // the beginning of the loop.
8 t. ^% F5 s) r7 \- b( l, h$ e
6 N0 L8 U0 E! J; V6 r' U, T" S    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
2 a2 F7 N/ m2 @9 w. U6 Z# j% P    // complicated schedules.
, P& L8 b1 B! _  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
' j0 F+ R' P4 P& y& P" ^% u/ z1 E9 w        
    return this;
& ^$ v: n: A0 c) ^0 r  }