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From: diamond@jit345.swstokyo.dec.com (Norman Diamond)
Newsgroups: comp.lang.misc
Subject: Re: Run-time Type Errors in Smalltalk
Message-ID: <1991Apr24.035448.28657@tkou02.enet.dec.com>
Date: 24 Apr 91 03:54:48 GMT
References: <1917@optima.cs.arizona.edu>
Sender: usenet@tkou02.enet.dec.com (USENET News System)
Reply-To: diamond@jit345.enet@tkou02.enet.dec.com (Norman Diamond)
Organization: Digital Equipment Corporation Japan , Tokyo
Lines: 22

In article <1917@optima.cs.arizona.edu> gudeman@cs.arizona.edu (David Gudeman) writes:
>In article  <1991Apr15.065146.16680@tkou02.enet.dec.com> Norman Diamond writes:
>>In article <4243.2805b94a@iccgcc.decnet.ab.com> klimas@iccgcc.decnet.ab.com writes:
>>>	Some info that I picked up from a company doing a lot of big
>>>	project work with C++ (i.e. strong type checking language) was
>>>	that postmortems on their project revealed only 10% of their
>>>	errors were captured by strong type checking.
>>In any other field of engineering, a 10% increase in safety would always
>>be applied.  To reject it would be grounds for lawsuits, at least.
>How do you get a 10% increase in safety from the above?  If they
>hadn't caught those errors by static typing they would have caught
>them by testing -- the same way the found the other 90% of the errors.

Sorry for the delay -- I have just discovered that topics which I reply to
in comp.object somehow move into comp.lang.misc, sigh.

Anyway, 10% of the caught errors were type errors.
By grossly rough estimate, 10% of the uncaught errors are also type errors.
Strong typing would reduce the number of remaining, uncaught errors by 10%.
--
Norman Diamond       diamond@tkov50.enet.dec.com
If this were the company's opinion, I wouldn't be allowed to post it.