Final Exam Review - Summer 2002

eXtreme Programming

1. "XP programmers don't document their code!?! How can their code still be readable after they write it?"



2. "What in the world do they mean that code written by an individual has to be thrown away? What other kind of code is there?"
   



3. "Integrating daily sounds like we'll spend all our time in integration. How can we make daily integration work more smoothly?"
   



4. "Is there any evidence that this really works?"

1. What is a design pattern?


2. Where did design patterns come from?


3. Name one design pattern and explain when you would want to use it.
   

You were hired to review the design and make suggestions for improvements on some object-oriented software. What would you say to each of the following and how would you fix any problems?

1. This class is the main class and handles many of the tasks.


2. We named the Warehouse class Ware becuase it is easier to type.


3. We are getting tons of code written becuase there are things we can just copy from similar classes.


4. We had one class inherit from another becuase the one class needed to access some information in the other class, but we had a problem that some of the inherited methods didn't make sense so we overrode them.


5. We have a type attribute in the Payment class and then we case (switch) on the type to handle billing by credit card, purchase order, create a bill, etc.
6. We had a guy who wanted to create about 10 classes but we found a way to do it in only 3!


7. We put most of the code into class methods and that way we don't need to create objects to do the work!

You want to extend your drawing editor so that it can be used by radiologist to mark-up a chest x-ray. The radiologist wants to load in a chest-xray and then add a shape (like a circle, polygon, etc) on an interesting spot in the x-ray. Then they want to annotate the shape with a sound file that describes what is interesting about the shape. They might also want to annotate the shape with the location and finding. Locations and findings can both have parents and children. For example a location is "Lungs". It has the parent "Chest". It has the children "Left Lung" and "Right Lung".

1. One tool that you are missing is a pen-like tool that will create a shape starting with the first mouse down and following the mouse until a mouse release. The shape will be a series of connected lines. How would your design change to add this tool?


2. Redraw the UML diagram to add the new classes you will need.

MVC vs. Morphic

(AbstractSound noteSequenceOn:
    (FMSound soundNamed: 'brass1')
    from: #((c4 1.0 500) (d4 1.0 500) (e4 1.0 5000))) play
    "Triplet are note, duration, and volume"

• "We usually have multiple teams of developers working on different parts of the programs at once. How does object-orientation help us with that?"
  
  
• "We rely heavily on simulation when developing sophisticated toys. What would be absolutely perfect would be if we could take parts of our simulation and use it in the code for the real toy. Can we do that? How?"
  
  
• "What happens if we develop add-ons for a toy, like a new Laser Gun for our Omega Video Game System? Or if we develop a new variation on a toy, like the Phaser Range Finder Gun (which is like the Laser Gun)? Can O-O help our productivity in doing this?"
  

Helping the Video Game Industry

Given your experience with designing and implementing epic adventure games, you have been hired as a consultant to Electronic Arts as they develop their response to the Myst series of adventure games.

• (5 points) The computer game and video game industry is enormous these days. EA realizes that there are two different potential markets for these games: The 12-18 year old market (low-budget, intense competition with movie industry), and the growing 25-40 year old market (can afford more expensive hardware). EA wants to know if they can have one user interface for both of these markets, or should they think about two user interfaces. How would you help them answer this question? What should they do before they start designing their user interface(s)?
• (5 points) Time passes, and now EA has some storyboards of the game and its interface. They want to know now, before they start coding and without spending too much money, if they're on the right path or have come up with a completely awful interface. What would you recommend they do and why?
• (10 points) EA is considering using a Model-View-Controller (MVC) structure for implementing the user interface for their new game. For example, if the user opens the Arkenchest, all the objects in the room touched by the evil ArkenLord should begin to glow. Trace out for EA the flow of messages in an MVC structure (assuming an object-oriented language, and that all objects in the visible world are View objects) between the user's opening the Arkenchest and the glowing of the objects.
• (5 points) EA used Squeak for their implementation, especially for the multimedia and portability aspects. Now they're looking to optimize some features. For example, parsing the 3-D objects is taking too long. Name at least two things that EA could try in order to speed up their code.

Design an Alarm System

• For any kind of alarm, you need to send all the alerts necessary for a given alarm. For example, for all fire alarms, the fire department is always called. The head of the house or business is always called for all alarm, and one or more "local experts" might also be called. For example, if there is a fire or intruder in the warehouse, the warehouse manager should also be called.
  
  
• You need to respond to Intruders by sounding the audio alarm in the vicinity. Assume that you just send the message trigger to the audio alarm object and it will sound.
  
  
• You need to respond to Fire by triggering the sprinklers in the vicinity, if available. Assume that you just send the message trigger to the sprinklers object.
  
  
• Your system is pretty sophisticated with respect to alerting authorities. It can handle IP or phone messaging. You can assume that the messaging is handled by another piece of the system. You need to provide the address of the authority (i.e., either a phone number or an email address) and the message to be sent (which should include, for example, the kind of alarm and the alarm vicinity).
  
  

• What classes do you need? What service do each need to provide? What attributes do each need to know?
  
  
• Where are there generalization-specialization relationships? Where are there part-whole relationships?
  
  

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• Reviews last edited on 24 July 2007 at 2:44 pm by balladeer.cc.gatech.edu