How to integrate a Pen class into a Turtle

I must create a Pen class which has properties color and width, and then use that in my Turtle3 class by using a setPen() method on it This is what I have so far:

1)My Pen Class

classdef Pen

      properties
          color 
          width
      end

      methods

          function obj=Pen()
          end

          function obj=setColor(obj,newColor)
              obj.color= newColor
          end

          function obj=setWidth(obj,newWidth)
              obj.width= newWidth
          end

      end

end

2) My Turtle3 class

classdef Turtle3
    %TURTLE Turtle with a pen
    %Turtle with a pen
    properties
        %location of turtle
        x
        y
        %0 is E, 90 is N, 180 is W, 270 is S
        heading
        %pen status
        pen_on_paper
        %pen
        pen
    end
    methods
        function obj=Turtle()
            %make a new Turtle
            obj.x=0;
            obj.y=0;
            obj.heading=90;
            obj.pen_on_paper= true;
            obj.pen = true;
            obj.pen = true;
        end

          function obj=forward(obj,distance)
              %move forward in current heading given distance
              x2=obj.x+distance*cosd(obj.heading);
              y2=obj.y+distance*sind(obj.heading);
              if obj.pen_on_paper
                  %draw line
                  hold on
                  l= line([obj.x x2], [obj.y y2]);
                  l.Color='black';
                  l.LineWidth=1;
                  hold off
                  pause(0.1)
              end
              %update location
              obj.x=x2;
              obj.y=y2;
          end

          function obj = rotate(obj,angle)
              % rotate CCW by given angle
              obj.heading = mod(obj.heading + angle,360);
          end

          function obj = penUp(obj)
              obj.pen_on_paper = false;
          end

          function obj = penDown(obj)
              obj.pen_on_paper = true;
          end

          function obj = setPen(obj, s)
              obj.pen= Pen();
          end

      end 
  end

I tried to run it using the following code:

thick_red = Pen();
thick_red = thick_red.setColor('red');
thick_red = thick_red.setWidth(5);
thin_blue = Pen();
thin_blue = thin_blue.setColor('blue');
thin_blue = thin_blue.setWidth(1);
turtle = Turtle3.setPen(thick_red);

The error that I am getting says "The class Turtle3 has no Constant property or Static method named 'setPen'.

Error in Triangle (line 16)
turtle = Turtle3.setPen(thick_red);"

[Walter Roberson]

Are you finished with http://www.mathworks.com/matlabcentral/answers/307747-create-a-pen-class-and-integrate-it-into-turtle and http://www.mathworks.com/matlabcentral/answers/307697-create-a-pen-class-and-integrate-it-into-turtle ?

Answer 1

[Soma Ardhanareeswaran]

'setPen' is a member function and not static. Invoke it using the object of the Turtle3 class.

[Estefania Dimas Martinez]

How do I do that?

[Walter Roberson]

t = Turtle3.Turtle();
t.setPen(thick_red);

Answer 2

[David Davis]

your setPen function is wrong. it Should look like this

function obj = setPen(obj,pen) obj.pen = pen; end

and then once you have done this you do what the person above says. You create a pen, establish its properties, create a turtle and then set the pen variable to be the turtles pen. Ex:

t = Turtle();

p = Pen();

red = p.setPen('red',2); % note I did both width and color in the same function

t.setPen(red);

Now your turtle will have a red pen.