Introductory Programming
Fall 2004

For next time you should:

1) Finish Homework 4.

2) Prepare for an evaluation on Chapter 4.

3) Start Chapter 5.



Functions
---------

What's up with functions?


Evaluation 2b solution:

def vee(t, n):
    # draws a V and leaves the turtle facing in the original direction
    rt(t, 45)
    fd(t, n)
    lt(t, 90)
    ft(t, n)
    rt(t, 45)

def double_yoo(t, n):
    vee(t, n)
    vee(t, n)



Refactoring
-----------

Read the following program to get an idea of what it does:

world.clear()
bob = Turtle(world)
bob.delay = 0.001
bob.x = -150
bob.y = 90
bob.redraw()

def koch(t, n):
    if n<5:
        fd(t, n)
        return
    n = n/3.0
    koch(t, n)
    lt(t, 60)
    koch(t, n)
    rt(t, 120)
    koch(t, n)
    lt(t, 60)
    koch(t, n)

for i in range(3):
    koch(bob, 300)
    rt(bob, 120)


On this or a separate piece of paper, write an improved version
of the program by following the instructions below.

1)  Encapsulate the last three lines in a function named
    snowflake.

2)  Generalize snowflake with appropriate parameters.

3)  Refactor koch to eliminate repetitive code.

4)  Apply any other transformations that you think would improve
    the program.