avatarsdev-general Mailing List for Avatars Development: the selfish game! (Page 3)

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On Tue, 3 Jun 2003, Inglima Modica Davide Silvio wrote:

> Modifiers and ids -- K - 2003 03 18

> 1) Modifiers: "Modifiers" means the way I chose to apply changes to
> entities in the game. That changes could be temporary ("transient") or
> can be not-reversible ("permanent").

[snip]

The problem is: what do you think a modifier has to do?
* Does it have to work as a netbeans/eclipse/mozilla plugin component?
* Does it have instead to work a simple "modifier" for the outcome of an
  action?

In the first case the chaos ensues, but in the second case it is
rather simple.

You have a modifier which:

(a) registers (enters a stack)
(b) unregisters

let's say to have a man with "Strenght" as one of his characteristics,
then there is a stack of modifiers somewhere.

To get the raw or modified strenght we have these member functions:

int getStrenghtRaw() {
   return strenght;
}

int getStrenghtModified() {
  int tempvalue = processStrenght(strengh);
  return validate(tempvalue);
}

To add a modifier we use a Collection:

List strenghtPile;

void strenghtModifiersPile(StrenghtModifier x) {
/// should throw an exception in case of duplicate modifier
  strenghtPile.add(x);
}

To use the modifiers then we iterate on it:

int processStrenght(int strenght) {
/// of course it could access directly strenght, but maybe we want
/// a little more freedom...

/*
 * insert classic iterator example here
 * since I'm trying to remember things...
 */
   Iterator i = strenghtPile.getIterator()
   while(i.hasnext()) {
     strenght = i.getNext().getModifierAction(strenght);
   }
   return strenght;
}

Modifiers then could be added or removed when needed

>     We need a way to identify the modifier to remove.
>     [ADD] I need some explanation: how the universe is supposed to
>     work? The "universe" has many "worlds" (one per runtime environment)
>     connected, and an entity can travel from one to another
>     on the net (ie over TCP/IP, etc.)? [ADD]

[snip]

>    3.1) What can be used as id in Java?

[snip]

>         [ADD] 4- java.rmi.server.UID [ADD]

Could be useful (the classes you propose are in J2SE if I'm correct,
right?).

Anyway...

IDManager could be a singleton class.

A singleton is a design pattern which says: "for each running instance of
program x there is only a given object of a given singleton class", so
having only one IDManager we can keep track of consistencies and
inconsistencies.

If we ever need to have a set of local and distributed IDManagers, the
local IDManager could call a central server IDManager which will give back
a pool of 100/1000 id's at a time.

How to write a singleton:

package net.sourceforge.avatars.util;

public class IDManager {
  private static IDManager idmanager = null;
  private int lastid = 0;

  // note the private constructor
  private IDManager() {
  }

  // this creates a new IDManager OR returns the IDManager already running
  public static IDManager getInstance() {
    if (idmanager == null) {
      idmanager = new IDManager();
    }
    return idmanager;
  }

  // this returns a number and adds one to the count;
  public synchronized Integer getNewID() {
     Integer result = new Integer(lastid);
     lastid++;
     return result;
  }
}

How to access it:

IDManager idm = IDManager.getInstance();
Integer   ix = idm.getNewID();

If we need to scale the IDs to a number higher, we could give back
a class with four integers, or whatevere other else.

Do we really need to free the IDs after having used them?

Ciao.
-- 
                   Davide Silvio Inglima-Modica
         "Mana is rapidly disappearing from the world, Even the"
          "mana tree has begun to wither" - Seiken Densetsu 3
                http://web.tiscali.it/inglima/davide/
                    mailto:had...@li...

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avatarsdev-general Mailing List for Avatars Development: the selfish game! (Page 3)

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