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[extremeprogramming] Re: Elves in the Night [Stupid XP Question Number 6614]

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  • Robert C. Martin
    wrote in message news:3871a37a.321644360@news.newsguy.com... ... what you ... Might ... waterfall ... I look at it differently than that.
    Message 1 of 38 , Jan 3, 2000
      <brougham2@...> wrote in message
      news:3871a37a.321644360@......

      > If you've already solved a problem before so that you already know
      what
      you
      > need to do, I don't see any benefit to XP's incremental development.
      Might
      > as well develop the infrastructure you *know* you will need via a
      waterfall
      > model, and then switch over to XP after that.

      I look at it differently than that. If I already knew the domain cold,
      I
      would still use XP simply because XP will give me the simplest design
      that
      could possibly work. I might be *sure* about all the infrastructure
      I'll
      need, but XP will only let me add it if its truly needed. And there can
      be
      a big difference between what I'm sure will be needed, and what really
      is
      needed.

      > I think what XP is saying is that if you aren't experienced enough in
      the
      > problem domain to know everything before hand, you will probably be
      better
      > off by deferring as many decisions as possible.

      I'd amend that to simply: "You are always better off deferring as many
      decisions as possible."

      > Incremental development isn't necessarily the best solution for *all*
      > problems.

      True. If the cost of change is very high, then we don't want to
      iterate.
      But if we can keep the cost of change low, through unit tests,
      refactoring,
      pair programming, and simplicity, then iteration is probably the best
      approach.


      --

      Robert C. Martin | OO Mentoring | Training Courses:
      Object Mentor Inc. | rmartin@... | OOD, Patterns, C++,
      Java,
      PO Box 85 | Tel: (800) 338-6716 | Extreme Programming.
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      http://www.objectmentor.com

      "One of the great commandments of science is:
      'Mistrust arguments from authority.'" -- Carl Sagan
    • Robert C. Martin
      Tom Kreitzberg wrote in message news:387364E4.C0A3E6CC@jhuapl.edu... ... There is no fundamental difference between pre XP Object
      Message 38 of 38 , Jan 5, 2000
        Tom Kreitzberg <Tom.Kreitzberg@...> wrote in message
        news:387364E4.C0A3E6CC@......

        > But I think "flexibility" means different things to XP and,
        > shall we say, pre-XP OMA. In XP, doesn't it primarily mean
        > once and only once? In pre-XP OMA, doesn't it primarily mean
        > OCP and low coupling? When I wrote that XP "is structured so
        > that inflexible designs are cheap to change," I meant inflexible
        > in this second sense.

        There is no fundamental difference between pre XP Object Mentor, and
        post XP
        Object Mentor except that we have identified XP as the process we like
        to
        use. Even this is not a big shift for us, since XP is very similar in
        spirit and practice to the unnamed process we have used for years.
        There
        are differences, certainly -- specifically in the areas of pair
        programming
        and test first programming; but these are differences in intensity, not
        in
        philosophy. As for the rules governing simplity, the planning game,
        quick
        iterations, etc, we were very closely aligned.

        Flexibility means the same to me now as it did five years ago. The
        ability
        to add or change significant amounts of functionality while changing a
        minimum of exsiting code -- i.e. the OCP. OnceAndOnlyOnce leads to this
        goal just as the OO design principles do. It is my goal over the next
        several months to integrate the principles and XP.
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