Re: Building objects on the fly

[Jae Chan Oh]

> 
> 
> joh> Do we need to use "buildObjects" whenever creating a new object?
> 
> To this question, I give a resounding "No!"  Not only is it
> unecessary to "build" all the objects in a swarm in a special
> "buildObjects" method; but, *I* claim that it can sometimes 
> be very artificial to do so.  (I have no idea if anybody agrees
> with me on this, so don't take my word as an expert.)
> 


Thanks, Glen, that's what I'm doing now. So nice to be able to make sure 
that what I'm doing is right. :-) 

Still some questions arise though.


> 
>   [myModelSchedule at: getCurrentTime() +1 createActionTo: self
>                        message M(giveBirthWithGenome:) : (id)genome];


In my simulation, the Model Swarm does not know -- at least not directly --
about births of individuals.
The simulation is like people running around in the world, if it happen to
bump into a likable person, they mate -- therefore, each person only
knows about birth of its child, much like the real world situation.

Now when a child is created, the genome for the child is also created.
Since I'm using GA lib written by J.J. Merelo -- I have modified/added
some functionality though --, the genome is also an object. So that
I would need to create the genome when creating a Person as well.
Here's how I do it.

-mateWith:  (id) person // person is ptr to the person I want to mate with
  {
  Person * child;

 // some stuff deleted 


// OK, NOW generate a offspring

  child = [self createChild];

  [[child getPersonDNA]  Mate: [self getPersonDNA]  And: [person getPersonDNA]
                         withMutation: MUTATION_RATE];
 return self;
}



*********** Then in my createChild,

-(id) createChild
 {
    Person * child;
    child = [Person createBegin: [self getZone]];


    ..... setup some stufF

    [child setPerson: id];   // create dna, set-up something...

    // tell the child where she is
    [child setWorld: pplPresent World: world ReaperQ: reaperQueue];


    ..... setup some stufF

    // finish the create phase
    child = [child createEnd];

    // add the child to the list of people
    [pplPresent addLast: child];

  return (id) child;
}


And in setPerson

-setPerson: (int) n
  {
  iD = n;
  numOfFriends = 0;  // no friends made so far
  live = TRUE;          // yes, it has just born

  //  create Chromosomes etc
  dna  = [BinChromosome createBegin: [self getZone]];
  [[dna setLength:  (int) (GEN_LENGTH/8)] setRandomInit];
  dna = [dna createEnd];
  [self setEvalFuncFromModel];

  return self;
  }


Do you see anything wrong in the above code? 

Also one more question about your code below...
What is myParentSwarm? Can I use [self getZone] instead? That's what I'm
doing. Whenever I need an object whether the new object is logically
belongs to another object -- like in the case of Person object and
Genome Object above -- I get a new Zone using [self getZone] message.
Is it OK? I thought about using [dna getZone] but that doesn't seem to work.


> 
> Then in the Person class, you might have the method:
> 
>   -(id) giveBirthWithGenome: (id) genome {
>      id newPerson;
> 
>    [ ... blahblahblah ...]
> 
>      newPerson = [Person createBegin: myParentSwarm];
                                       ^^^^^^^^^^^^^^^^
                                      So why this, instead of [self getZone]?


> 
> Now, there should be some message that the modelSwarm can 
> accept to tell it to add the new person to the appropriate
> lists and the space and such.  But, the creation of the 
> individuals should be abstracted from the system you're trying
> to model.

Well, as I said above, I add new persons in Person.m. Do you mean that
I have to let the ModelSwarm know about the adding the new Person explictly
using a method? Since the pointer pplList is known to both ModelSwarm and 
Person objects, wouldn't it reflect the changes in pplList from the ModelSwarm's
view if we change the pplList in a Person object?(i.e. adding a new Person)


Thank you very much for your help!


-Jae