Abstraction

Have a look at these geometric figures:

A	B	C	D	E

We could call them rounded edges. Here are some similarities:

• They all are horizontal.
• They all have quarter-circle caps at the ends, rounded at the top, straight at the bottom.

You might argue that figure C, the yellow semicircle, is hardly a rounded edge. Hold that thought!

Now let's focus on their differences, so we can figure out what parameters a rounded_edge function should have.

def rounded_edge(...) -> Graphic:

We can see that the color differs, so we want to have a parameter to specify the color.

Besides the color, there's also the length and thickness.

We need to decide how we measure the length. Different from the rounded_line function you might have implemented before, here we measure the total_length, which includes the caps.

def rounded_edge(total_length: float, thickness: float, color: Color) -> Graphic:

Note that the line's thickness determines the radius of the caps.

Implement

Play With Parameters

Play with your rounded_edge function, creating lines with different sizes and colors.

Can you create a semicircle?

Does the smallest possible total_length depend on the thickness? If yes, how? You may want to add an assertion to your rounded_line function to ensure that the total_length is acceptable.

Save in Toolbox

Save your rounded_edge function in your toolbox. It will come in handy in various ways, for example as a component of a Rounded Rectangle.