->proj10;

Overview¶

This week’s project is to extend your Java, Ada, and Ruby class hierarchies with some new classes:

• A Penguin class

• An Ostrich class

• A Kiwi class

which are described further below. Note that we will not be using Clojure in this project, because as a functional language, it really isn’t intended to support object-oriented programming and class hierarchies.

Class Hierarchy Exercise¶

As in the lab exercise, each kind of bird should respond appropriately to name() and call() messages. However, where owls, geese, and ducks are flying birds, penguins, ostriches, and kiwis are non-flying birds, so you are to modify things such that (for example) C++ code like this:

Bird * birdPtr0 = new Duck("Donald");
Bird * birdPtr1 = new Penguin("Peter");
Bird * birdPtr2 = new Goose("Mother");
Bird * birdPtr3 = new Ostrich("Orville");
...
birdPtr0->print();
birdPtr1->print();
birdPtr2->print();
birdPtr3->print();
...

will produce output like this:

Donald Duck just flew past and said, "Quack"
Peter Penguin just walked past and said, "Huh-huh-huh-huuuuh"
Mother Goose just flew past and said, "Honk"
Orville Ostrich just walked past and said, "Snork"
...

(You can make up your own call for a kiwi.)

To make all of this happen with a minimal amount of code, you are to rewrite the print() method in class Bird to be something like the following:

inline void Bird::print(ostream & out) const {
   out << name() 
        << ' ' 
       << className() 
       << " just "
       << movement()
       << " and said " 
       << call();
} 

In order for this to work, you should:

1. add an abstract movement() message to class Bird;

2. define two new subclasses of Bird named FlyingBird and WalkingBird;

3. have each of these subclasses define movement() appropriately;

4. revise the definitions of classes Owl, Duck, and Goose to make them subclasses of FlyingBird; and

5. define classes Penguin, Ostrich, and Kiwi as subclasses of WalkingBird.

You will need to research how to go about creating an abstract method in each language.

The resulting class hierarchy should look something like this:

Testing¶

In each language, modify the birds program so that it demonstrates that your class hierarchy works correctly. Make certain that it creates instances of all six ‘leaf’ classes in the hierarchy.

Submission¶

Accept the project invitation from GitHub Classroom. Clone the repository and open it in your editor. Extend the bird hierarchy with the new classes in Java, Ada, and Ruby. Commit and push your work to your repository.

Rubric¶