Ilja Preuss wrote:
> Edmund Schweppe wrote:
>>I haven't got Kent's White Book in front of me, and I don't have
>>Barry's paper anywhere, so I'm speaking from oft-fragile memory here,
>>AFAIK, Barry Boehm's research showed the cost of *fixing defects* grew
>>AFAIK, Kent Beck's assertion is that the cost of *making changes*
>>under XP does not grow exponentially.
>>AFAIK, *fixing defects* != *making changes*. More specifically, there
>>exist changes to software that do not involve fixing existing defects.
>>(Obviously, fixing a defect involves making a change. Somewhere.)
> I am not at all sure that Barry made this distinction.
I don't think he did either - and that's where I suspect a big part of
the problem lies. I keep on seeing references to cost-of-*change* curves
which talk about how expensive fixing *mistakes* are.
> Actually I'd
> think that having to "make a change" invariably had to be a reaction to
> a "defect in the requirements" for him. At least that's the only way I
> can imagine introducing a "bug" in the "analysis phase" at all...
I can imagine two scenarios:
1) When I'm initially gathering requirements from you, you tell me that
the app needs to display information in both English and German. I
misunderstand you (or lose my notes) and deliver an English-only app.
That would be a "requirements bug".
2) When I'm initially gathering requirements from you, you tell me that
the app needs to display information in English. I deliver an
English-only app; then you tell me that you also need the app to display
information in German. (For instance, you might have been building a
payroll system for an American automotive manufacturer who subsequently
was purchased by a German one :-) That, to me, is a change that's not
due to a bug in the requirements; instead, it's due to a change in the
> Take care, Ilja
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Edmund Schweppe -- schweppe@...
The opinions expressed herein are at best coincidentally related to
those of any past, present or future employer.