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From: ogden@seal.cis.ohio-state.edu (William F Ogden)
Newsgroups: comp.software-eng
Subject: Re: Reusability considered harmful??(!!)
Message-ID: <88637@tut.cis.ohio-state.edu>
Date: 19 Feb 91 19:28:41 GMT
References: <88431@tut.cis.ohio-state.edu> <6108@stpstn.UUCP> <1127@TALOS.UUCP> <1991Feb18.224524.28236@cbnewsm.att.com>
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Reply-To: William F Ogden <ogden@cis.ohio-state.edu>
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Lee Derbenwick writes:
    ....
#The data book helps, but it still never does the complete job.  The
#sine routine that someone else mentioned is a good example: its behavior
#was good enough on average, but its worst-case error happened to be
#around the most critical values for one application.  The spec sheet
#is not normally going to give you a chart of error tolerance (or time
#delay, or whatever) vs. input values.  ....

I say that if you really want reusable software components, then
you're going to view a spec for a sine routine that doesn't include
error tolerances (or execution times, etc.) as simply inadequately
specified.


#Do you buy a car without a test drive?  Do you buy a suit without trying
#it on?

For peace of mind, you may want to take it out for a test drive, but
you really can't afford to test whether it meets all its specs. Do
you check the oil capacity, the generator output, the compression ratio,
the horsepower rating, etc.? When buying clothing, do you check the 
durability, colorfastness, shrikage, wrinkle resistance, etc.?

/Bill