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CS253 Delivery

What Computer Programmers Do

Computer programmers don’t just program.

Bakers

• Bakers don’t just bake bread. They may:
  • clean the bakery
  • deal with employees
  • purchase ingredients
  • obey food/restaurant regulations
  • research new recipes
  • bake bread
  • present bread attractively
  • set prices
  • deal with credit card companies
  • deal with banks for checks
  • pay taxes
• They love baking bread, and would prefer to do that full time, but that’s the nature of the business.

Programmers

• Similarly, computer programmers don’t just write code. They may:
  • learn new algorithms
  • write specifications
  • design code
  • write code
  • debug code
  • test code
  • package code
  • deliver code
  • support old code

CS253

• In this class, I will handle writing specifications, but you must:
  • design code
  • write code
  • debug code
  • test code
  • package code
  • deliver code
  • support old code

Problems

• Design:
  • My students don’t give design its due.
  • They think that they can do design jointly.
  • That’s a fatal error.
• Packaging:
  • My students generally allocate about five minutes before the due time to figure out how to do the packaging.
  • Therefore, they often get the packaging wrong.
  • This makes me sad, and them sadder.
• Delivery:
  • My students tend to do OK at delivery.
  • However, then don’t always read all the error messages, and so don’t notice when the submission is rejected.

🍕

The other night, I called the local pizza parlor and ordered a large pizza, with mushrooms & peppers, to be delivered at 7:00ᴘᴍ, costing $20. By 8:00ᴘᴍ, I gave up, and called them back:

Me: Where’s my pizza? PP: Large, mushrooms & peppers? Me: Yes. PP: I made it. It’s here. Me: Maybe … I dunno … deliver it?!   PP: Oh, yeah. Sorry. I forgot. Me: @#%$☠^&*! PP: That’ll be $20. Me: What?

PP: I made your pizza. You owe me $20. Me: You didn’t deliver it! PP: Yeah, that’s true. How about $10? Me: YOU GET NOTHING! PP: I made it perfectly! That’s what counts! Me: I think that delivery is important. PP: You can’t take away all the money for one problem! Me: You. Didn’t. Deliver. It. PP: But I worked really hard on that pizza! >slam<

The Pizza Product

• It all comes down to defining The Product.
• The pizza chef might wish to define their product as a pizza, because they’re really into pizza cooking, but that’s wrong.
• The real product for a pizza delivery company is:
  • a good-tasting pizza
  • with the right toppings
  • delivered to the right place
  • at the right time
• If any of those elements aren’t satisfied, the customer is unhappy.

The Programming Product

• It all comes down to defining The Product.
• A programmer might wish to define their product as the source file that contains the main program, because they’re really into programming, but that’s wrong.
• The real product for a programmer is:
  • all the necessary source code (source files, header files)
  • the overhead files (e.g., Makefile, data files)
  • correctly packaged (e.g., a tar file)
  • turned in on time

Testing Pizza

• A good pizza delivery service will test their actual product, the delivered-on-time correct pizza.
• They would be foolish to only taste-test the pizza in the shop, and never test the delivery process.
• They would secretly order a pizza, pretending to be a customer, and test how long it takes to arrive at the destination, is it correct, hot, tasty, etc.

Testing Software

• Similarly, a good student will test their actual product, the on-time tar file.
• They would be foolish to only test their source code in the directory where they developed it.
• They would untar their tar file, pretending to be the grader, build the test case, and verify that it works.