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  1. #1

    Once upon a time

    Once upon a time, in a kingdom not far from here, a king summoned two
    of his
    advisors 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.
    king asked, "How would you design an embedded computer for it?" The
    replied, "Using a four-bit microcontroller, I would write a simple
    that reads the darkness knob and quantises its position to one of 6
    of darkness, from snow white to coal black. The program would use that
    darkness level as an index to a 16-element table of initial timer
    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
    show you a working prototype."

    The second advisor, a computer scientist, immediately recognised the
    of such short-sighted thinking. He said, "Toasters don't just turn
    into toast, they are also used to warm frozen waffles. What you see
    you is really a breakfast food cooker. As the subjects of your kingdom
    become more sophisticated, they will demand more capabilities. They
    need a breakfast food cooker that can also cook sausage, fry bacon, and
    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. Specialise this
    into subclasses: grains, pork and poultry. The specialisation process
    be repeated with grains divided into toast, muffins, pancakes and
    pork divided into sausage, links and bacon; and poultry divided into
    scrambled eggs, hard-boiled eggs, poached eggs, fried eggs and various
    omelette classes."

    "The ham and cheese omelette class is worth special attention because
    must inherit characteristics from the pork, dairy and poultry classes.
    we see that the problem cannot be properly solved without multiple
    inheritance. At run time the program must create the proper object and
    a message to the object that says, 'Cook yourself.' The semantics of
    message depend, of course, on the kind of object, so they have a
    meaning to a piece of toast than to scrambled eggs."

    "Reviewing the process so far, we see that the analysis phase has
    that the primary requirement is to cook any kind of breakfast food. In
    design phase we have discovered some derived requirements.
    Specifically, we
    need an object-oriented language with multiple inheritance. Of course,
    don't want the eggs to get cold while the bacon is frying, so
    processing is required, too."

    "We must not forget the user interface. The lever that lowers the food
    versatility and the darkness knob is confusing. Users won't buy the
    unless it has a user-friendly graphical interface. When the breakfast
    is plugged in, users should see a cowboy boot on the screen. Users
    click on it and the message 'Booting UNIX v. 8.3' appears on the
    screen.(UNIX 8.3 should be out by the time the product gets to the
    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
    the implementation phase. An Intel Pentium with 32MB of memory, a 500MB
    disk and 17inch SVGA monitor should be sufficient. If you select a
    multi-tasking, object-oriented language that supports multiple
    and has a built-in GUI, writing the program will be a snap. (Imagine
    difficulty we would have had if we had foolishly allowed a
    design strategy to lock us into a four-bit microcontroller!)."

    The king wisely had the computer scientist beheaded, and they all lived
    happily ever after.

    Extreme Testing-the best way to survive extreme change.
    Extreme Testing-the best way to survive extreme change.

  2. #2

    Re: Once upon a time

    Yeah... Well, breakfast IS the most important meal of the day....

    "I can see my house from here!"
    Jordan Gottlieb - Keeper of the QA Forums FAQ
    Qualitech Solutions, Inc.
    Jordan Gottlieb
    Senior Consultant, Orasi Software
    Twitter: @JG_QA



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