Archive - Jul 2005

Date
  • All
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31

The Parable of the OOP and Breakfast

Once upon a time, in a kingdom not far from here, a king summoned two of his advisers for a test. He showed them both a shiny metal box with two slots in the top, a control knob, and a lever. "What do you think this is?"

One advisor, an engineer, answered first. "It is a toaster," he said. The king asked, "How would you design an embedded computer for it?" The engineer replied, "Using a four-bit microcontroller, I would write a simple program that reads the darkness knob and quantizes its position to one of 16 shades of darkness, from snow white to coal black. The program would use that darkness level as the index to a 16-element table of initial timer values. Then it would turn on the heating elements and start the timer with the initial value selected from the table. At the end of the time delay, it would turn off the heat and pop up the toast. Come back next week, and I'll show you a working prototype."

The second advisor, a ColdFusion developer, highly skilled in Mach-II, Model-Glue and Java, immediately recognized the danger of such short-sighted thinking. He said, "Toasters don't just turn bread into toast, they are also used to warm frozen waffles. What you see before you is really a breakfast food cooker. As the subjects of your kingdom become more sophisticated, they will demand more capabilities. They will need a breakfast food cooker that can also cook sausage, fry bacon, and make scrambled eggs. A toaster that only makes toast will soon be obsolete. If we don't look to the future, we will have to completely redesign the toaster in just a few years."

"With this in mind, we can formulate a more intelligent solution to the problem. First, create a class of breakfast foods. Specialize this class into subclasses: grains, pork, and poultry. The specialization process should be repeated with grains divided into toast, muffins, pancakes, and waffles; pork divided into sausage, links, and bacon; and poultry divided into scrambled eggs, hard-boiled eggs, poached eggs, fried eggs, and various omelet classes."

"The ham and cheese omelet class is worth special attention because it must inherit characteristics from the pork, dairy, and poultry classes. Thus, we see that the problem cannot be properly solved without multiple inheritance. At run time, the program must create the proper object and send a message to the object that says, `Cook yourself.' The semantics of this message depend, of course, on the kind of object, so they have a different meaning to a piece of toast than to scrambled eggs." "Reviewing the process so far, we see that the analysis phase has revealed that the primary requirement is to cook any kind of breakfast food. In the design phase, we have discovered some derived requirements. Specifically, we need an object-oriented language with multiple inheritance. Of course, users don't want the eggs to get cold while the bacon is frying, so concurrent processing is required, too."

"We must not forget the user interface. The lever that lowers the food lacks versatility, and the darkness knob is confusing. Users won't buy the product unless it has a user-friendly, graphical interface. When the breakfast cooker is plugged in, users should see a cowboy boot on the screen. Users click on it, and the message `Booting Application Breakfast v1.2' appears on the screen. (Breakfast v1.2 should be out by the time the product gets to the market.) Users can pull down a menu and click on the foods they want to cook."

"Having made the wise decision of specifying the software first in the design phase, all that remains is to pick an adequate hardware platform for the implementation phase. An Intel Pentium 1.86GHz with 1.2GB of memory, a 220GB hard disk, and a TFT monitor should be sufficient. Selecting a multitasking, object oriented language that supports multiple inheritance and has a built-in GUI, means writing the program will be a snap. (Imagine the difficulty we would have had if we had foolishly allowed a hardware-first design strategy to lock us into a four-bit microcontroller!)."

The king had the computer scientist thrown in the moat, and they all lived happily ever after.

(Thanks to Mike Kear)

Odd conversations you find yourself having

All I said about shoot-to-kill was
Incidently, feel free to cut me up once I've passed away and hand the bits out to other people. I carry a card, but the government is too busy having innocent people shot dead to sort the law out, so they'll have to ask you anyway.
And Dad comes back with

Sprinting away when the police announce their presence and leap-frogging over ticket barriers are not actions of an innocent person.

Says I

Should it be punishable by death though ?
More to the point, how I would have laughed if the imaginary suicide bomber had had an imaginary 'dead mans handle' and the imaginary bomb had gone off when his heart stopped.

I notice the government have also announced plans to burn books (and shops) who say things they don't like.

Great.

Jarre@Poland

Gah. Tickets for concert (the one we have a hotel and flights for allready) delayed till Wednesday. And again till Thursday. Feel my pain !

Also it's possible that rehearsal signing session , but I've promised to say nothing :-)

Dear Blair

Please don't stand up and say stupid things like 'we will not allow violence to change our society or values' when that is exactly what you and bush did in Iraq.

On: liberty

You've seen the film, http://eclectech.co.uk/clarkeidcards.php now sign the pledge http://www.pledgebank.com/refuse :

"I will refuse to register for an ID card and will donate

topical-homopterousif you are reading this, don't click it as it will mark you as a spammer
if you are reading this, don't click it as it will mark you as a spammer