% File "active.tu".
%
% Written by Phil Edmonds, Feb 97.
%
% An active object is a kind of object that lives in the world, and takes
% an active part in the simulation
%
%+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

unit
class ActiveObject

    inherit Object in "object.tu"

    import World in "world.ti"

    export InitActiveObject, JoinWorld,   TakeTurn


    %========== INSTANCE VARIABLES ==============================
    %============================================================

    var frequency : int % how many time steps to wait before taking a turn
    var world : ^World % which world I'm in.

    %========== INITIALIZE ======================================
    %============================================================

    proc InitActiveObject (x, y : real, n : string, c : int, f : int)
        Object.Init (x, y, n, c)
        frequency := f
    end InitActiveObject

    %========== PUBLIC FUNCTIONS ================================
    %============================================================

    % A basic active object doesn't know how to take a turn in the
    % simulation, but its descendants should
    %------------------------------------------------------------
    deferred proc TakeTurn


    % Tells the object which world it is in, and adds itself to the
    % world
    %------------------------------------------------------------
    proc JoinWorld (w : ^World)
        world := w
        world -> AddDenizen (self)
    end JoinWorld

end ActiveObject