RandomMoveInGrid/notes-changing-program.txt
-------------------------------------------

Typical changes that one would make to this simple
program/model, or to any of the Demos-3/ programs
would involve adding new:
  - run-time settable parameters 
  - measures
  - functionality to agents
  - types of agents (eg classes)
  - displays, e.g. graphs, histograms, 2D displays, etc

For some of the above, see the handouts
   howTo-AddParameter.txt
   howTo-AddNewClass.txt

In general, the places to change are:

Model.java
----------
  - add instance variables
    - for run-time parameters
    - for lists of new kinds of agents
    - for storing values of measures calculated

  - setup()   - to "tear down" any objects you have built

  - buildModel()
    - to create new types of agents, etc
    * note: call other methods to avoid a really
            long buildModel() method

  - step() 
    - send messages to all agents, objects, to drive
      the basic step-wise dynamics of the model!
      (for discrete time models)

  - stepReport()
    - call methods to calculate measures
    - write those measures to the report file(s)

  - writeHeaderCommentsToReportFile()
    - to put text at top of columns of data in report file

  - printProjectHelp()
    - to write out more help/info when user enters -h parameter


GUIModel.java
-------------
  - add instance variables for display objects (eg, Graphs, etc)

  - setup() -- "tear down" any display objects

  - buildDisplay()
    create display objects (eg DisplaySurface) and create/link to
      "mapping" objects (e.g., Object2DDisplay, ColorMap, etc)

  - step()
    - send messages to any new display objects as needed