Contributed by Chris Rathman
begin class Shape(x, y); integer x; integer y; virtual: procedure draw; begin comment -- get the x & y components for the object --; integer procedure getX; getX := x; integer procedure getY; getY := y; comment -- set the x & y coordinates for the object --; integer procedure setX(newx); integer newx; x := newx; integer procedure setY(newy); integer newy; y := newy; comment -- move the x & y position of the object --; procedure moveTo(newx, newy); integer newx; integer newy; begin setX(newx); setY(newy); end moveTo; procedure rMoveTo(deltax, deltay); integer deltax; integer deltay; begin setX(deltax + getX); setY(deltay + getY); end moveTo; end Shape; Shape class Rectangle(width, height); integer width; integer height; begin comment -- get the width & height of the object --; integer procedure getWidth; getWidth := width; integer procedure getHeight; getHeight := height; comment -- set the width & height of the object --; integer procedure setWidth(newwidth); integer newwidth; width := newwidth; integer procedure setHeight(newheight); integer newheight; height := newheight; comment -- draw the rectangle --; procedure draw; begin Outtext("Drawing a Rectangle at:("); Outint(getX, 0); Outtext(","); Outint(getY, 0); Outtext("), width "); Outint(getWidth, 0); Outtext(", height "); Outint(getHeight, 0); Outimage; end draw; end Circle; Shape class Circle(radius); integer radius; begin comment -- get the radius of the object --; integer procedure getRadius; getRadius := radius; comment -- set the radius of the object --; integer procedure setRadius(newradius); integer newradius; radius := newradius; comment -- draw the circle --; procedure draw; begin Outtext("Drawing a Circle at:("); Outint(getX, 0); Outtext(","); Outint(getY, 0); Outtext("), radius "); Outint(getRadius, 0); Outimage; end draw; end Circle; comment -- declare the variables used --; ref(Shape) array scribble(1:2); ref(Rectangle) arectangle; integer i; comment -- populate the array with various shape instances --; scribble(1) :- new Rectangle(10, 20, 5, 6); scribble(2) :- new Circle(15, 25, 8); comment -- iterate through the list and handle shapes polymorphically --; for i := 1 step 1 until 2 do begin scribble(i).draw; scribble(i).rMoveTo(100, 100); scribble(i).draw; end; comment -- call a rectangle specific instance --; arectangle :- new Rectangle(0, 0, 15, 15); arectangle.draw; arectangle.setWidth(30); arectangle.draw; end |