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Re: Space probes was Re: in praise of type checking

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On 11-10-13 02:08 AM, Leif Roar Moldskred wrote:
> Gene Wirchenko <genew@ocis.net> wrote:
>>
>>     Sure there was.  It had an assumption about how much oomph the
>> rocket had.  The Ariane 5 had way more than the 4 did.  With the 4,
>> the overflow was not possible.  With the 5, it was.
> 
> Yes, but as the code wasn't written to be used on the Ariane 5, that
> was a valid assumption and not an error. The code was correct and fit
> for its intended use. That someone later took this code and tried to
> use it for something it was never meant to be used for is not an error
> in the code: A wrench makes a poor hammer, but that doesn't mean the
> wrench is constructed badly.
> 
When I read the report that Martin pointed us at, particularly pages 4-6
(pages 8-10 of the PDF), I sure don't get the impression that the code
was "correct and fit for its intended use". This includes in a wider
sense the documentation that describes the assumptions and decisions
related to the code.

How do you know that the code was not meant to be used for the Ariane 5?
They _did_ use it for the Ariane 5; that's enough evidence for me that
they intended for it to be used not just for the Ariane 4 but also for
the Ariane 5. The report clearly states that the reasoning related to
the horizontal bias variable BH was *faulty* - they just happened to be
fortunate with Ariane 4. It was not, as you suggest, a "valid
assumption". And the follow-up exception-handling was described as a
systematic software design error.

In a wider sense, if you've got a codebase that was intended for
situation A (or more precisely, since "intended" is a strong purposeful
word that implies knowing what you're about, "used with"), and now you
adopt it for situation B, that codebase _belongs_ to situation B. You
can't say it's fit and correct just because it still works in situation
A - who cares, actually? If it's unfit for situation B it's unfit for
situation B. Period.

AHS
-- 
I tend to watch a little TV... Court TV, once in a while. Some of the
cases I get interested in.
-- O. J. Simpson

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in praise of type checking Roedy Green <see_website@mindprod.com.invalid> - 2011-10-05 23:33 -0700
  Re: in praise of type checking Lew <lewbloch@gmail.com> - 2011-10-06 06:43 -0700
    Re: in praise of type checking Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-06 09:52 -0700
    Re: in praise of type checking Roedy Green <see_website@mindprod.com.invalid> - 2011-10-07 12:43 -0700
      Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-07 14:57 -0700
      Re: in praise of type checking Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-07 20:18 -0400
  Re: in praise of type checking Robert Klemme <shortcutter@googlemail.com> - 2011-10-06 22:31 +0200
    Re: in praise of type checking Roedy Green <see_website@mindprod.com.invalid> - 2011-10-07 12:36 -0700
      Re: in praise of type checking Robert Klemme <shortcutter@googlemail.com> - 2011-10-08 16:05 +0200
        Re: in praise of type checking Lew <lewbloch@gmail.com> - 2011-10-08 09:35 -0700
          Re: in praise of type checking Robert Klemme <shortcutter@googlemail.com> - 2011-10-11 07:48 +0200
            Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-11 13:04 -0700
            Re: in praise of type checking Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-10-11 17:52 -0300
              Re: in praise of type checking Patricia Shanahan <pats@acm.org> - 2011-10-12 01:49 +0100
                Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-11 19:12 -0700
            Re: in praise of type checking Lew <lewbloch@gmail.com> - 2011-10-11 19:10 -0700
  Re: in praise of type checking Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-06 20:29 -0400
    Re: in praise of type checking Robert Klemme <shortcutter@googlemail.com> - 2011-10-06 23:56 -0700
      Re: in praise of type checking Gunter Herrmann <notformail0106@earthlink.net> - 2011-10-07 13:57 -0400
  Re: in praise of type checking Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-10-07 07:19 -0300
    Re: in praise of type checking Roedy Green <see_website@mindprod.com.invalid> - 2011-10-07 12:39 -0700
      Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-07 15:03 -0700
        Space probes was Re: in praise of type checking Tom Anderson <twic@urchin.earth.li> - 2011-10-11 19:26 +0100
          Re: Space probes was Re: in praise of type checking Leif Roar Moldskred <leifm@dimnakorr.com> - 2011-10-12 01:15 -0500
            Re: Space probes was Re: in praise of type checking Travers Naran <tnaran@gmail.com> - 2011-10-12 07:23 -0700
            Re: Space probes was Re: in praise of type checking Martin Gregorie <martin@address-in-sig.invalid> - 2011-10-12 20:04 +0000
            Re: Space probes was Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-12 13:53 -0700
              Re: Space probes was Re: in praise of type checking Leif Roar Moldskred <leifm@dimnakorr.com> - 2011-10-12 16:55 -0500
                Re: Space probes was Re: in praise of type checking Gene Wirchenko <genew@ocis.net> - 2011-10-12 15:02 -0700
                Re: Space probes was Re: in praise of type checking Leif Roar Moldskred <leifm@dimnakorr.com> - 2011-10-13 00:08 -0500
                Re: Space probes was Re: in praise of type checking Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-10-13 07:48 -0300
                Re: Space probes was Re: in praise of type checking "John B. Matthews" <nospam@nospam.invalid> - 2011-10-14 07:09 -0400
                Re: Space probes was Re: in praise of type checking Martin Gregorie <martin@address-in-sig.invalid> - 2011-10-12 22:03 +0000
            Re: Space probes was Re: in praise of type checking Tom Anderson <twic@urchin.earth.li> - 2011-10-14 14:14 +0100
  Re: in praise of type checking RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-10-07 11:50 +0100
    Re: in praise of [loosey goosey] type checking) RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-10-07 12:20 +0100
  Re: in praise of type checking Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-10-07 14:00 +0000

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