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Re: Re[2]: [XP] The Cost of Change Curve

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  • yahoogroups@jhrothjr.com
    From: Doug Swartz To: Robert C. Martin
    Message 1 of 115 , Apr 1, 2004
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      From: "Doug Swartz" <daswartz.at.prodigy.net@...>
      To: "Robert C. Martin"
      Sent: Thursday, April 01, 2004 8:16 AM
      Subject: Re[2]: [XP] The Cost of Change Curve

      > Wednesday, March 31, 2004, 11:04:36 PM, Robert C. Martin wrote:
      > > Some folks have said that XP flattens the curve. I don't think that's
      > > I think that whatever flattening has taken place has been because of
      > > that are outside of XP's control. I think XP works *because* of this
      > > flattening; I don't think XP causes the flattening.
      > > What agency might have caused the flattening? Consider:
      > > The cost of change curve was measured by Boehm thirty years ago. Since
      > > time:
      > > * Computers are 1000 time faster.
      > > * Computers have 1000 times as much iternal storage.
      > > * Computers have 1000 times as much external storage.
      > > * Computers are 1000 times smaller by volume
      > > That's 12 (count them: TWELVE) orders of magnitude difference; and if we
      > > looked we could probably find three or four more. What difference do
      > > twelve zeros make?
      > > I don't have to wait overnight to compile a 1000 line program; instead I
      > > run hundreds of compiles every day.
      > > Every developer can have one or more of these 1,000,000,000X machines
      > > their own private use instead of sharing it with the whole department.
      > > These powerful machines support *tools* that help you edit your code,
      > > refactor your code, compile your code, test your code, package your
      > > deploy your code.
      > And XP and the other Agile approaches take advantage of these
      > environmental changes. It's, at least partly, a case of the
      > difference between a "culture of plenty" and a "culture of
      > scarcity". In our culture of plenty we tend to do things much
      > differently.
      > Therefore, I think I agree with Uncle Bob, that flattening the
      > change curve is the result of the practices we do. But the
      > practices wouldn't have been possible 35 years ago.

      In a sense that's true, but it's not a matter of scale, it's a
      matter that the increase in availible computing power lets
      us do something completely different with it. 35 years ago,
      when you could only get one compile and test run a day
      with your tray of punched cards, it made a great deal of sense
      to do thorough requirements analysis up front, followed by a
      complete design and only then go to code.

      The fact is that it's not the amount of computing horsepower,
      it's how it's applied. I could have done TDD on my Apple II
      25 years ago, for instance. I could have done TDD on my
      IBM mainframe using TSO 30 years ago if I'd had the tools

      John Roth

      > --
      > Doug Swartz
      > daswartz@...
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    • Ron Jeffries
      ... No clue what you re referring to. I can search if you can give me more context ... Ron Jeffries www.XProgramming.com Those who attain to any excellence
      Message 115 of 115 , Apr 8, 2004
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        On Wednesday, April 7, 2004, at 9:55:42 PM, Kay Pentecost wrote:

        > I haven't gotten a really good answer yet... Except for some qualities that
        > Ron Jeffries listed a while ago... which provide a good starting point.
        > Maybe Ron would list them again. I have them printed out on several pieces
        > of paper so I come across them when I'm looking for something else... but I
        > don't know where they are now.

        No clue what you're referring to. I can search if you can give me more
        context ...

        Ron Jeffries
        Those who attain to any excellence commonly spend life in some single
        pursuit, for excellence is not often gained upon easier terms.
        -- Samuel Johnson
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