From: Joe Van Dyk <joevandyk@...>
Date: 2005-07-13T02:55:54+09:00
Subject: Updating GUIs

Hi,

I'm still fairly new to writing GUIs.  A common approach to me is to
write some model classes that have a function called "update".  That
function should get called a few times a second, and then the GUI
should get updated reflecting those changes.

What's the best way to do this?  Should I have a Ruby thread that
calls the update function, sleeps for 0.2 seconds, and then loops? 
How should the GUI get notified of those changes?

For discussion purposes, say I have 

class Player
  attr_accessor :x_position, :y_position, :player_type
  # just a data store 
end

class PlayerList
  attr_accessor :players
  def initialize
    @players = [Player.new, Player.new, Player.new]
  end
  def update
    # update goes out and updates the x and y position
  end
end

And then the GUI knows about PlayerList and needs to display updated
information on each Player (move a player icon on a map, update
tabular data, that kind of thing).

I could have up to 500 players, and the application isn't supposed to
be terribly CPU intensive, so performance can be an issue.