Flying With Python (Strong versus Weak Typing)
knepley at mcs.anl.gov
Wed Mar 12 22:53:45 CET 2003
>>>>> ">" == Peter Hansen <peter at engcorp.com> writes:
>> Dennis Lee Bieber wrote:
>> laotseu fed this fish to the penguins on Tuesday 11 March 2003 06:41 pm: > Second thing : > Ariane crashed because
>> of a bug in an ADA module. ADA is very strongly > *and* statically typed.
>> The module was fine -- for the previous generation of Ariane.
>> If I read correctly, one of the reports available on-line, the closest one can come to is that the module which
>> failed was not coded to trap an exception condition and recover.
>> There was a lengthy discussion of this in the Extreme Programming mailing list at one point. I can't recall the
>> conclusion, but after rereading your quotations it seems to me that this is a case where adequate testing could
>> have "easily" identified the problem.
>> It would be interesting to know what tests where actually done, but my guess is that unit tests for the individual
>> routines involved was not one of them, or that those tests where quite inadequate (not checking behaviour in the
>> case of an out-of-bounds value, for example).
If you read the report cited closely, you will see that they did in fact identify
this location in their tests as something that could throw an out-of-bounds
exception (along with about 100 others), but chose not to protect it since the
cost of recoding was high. Some bets lose.
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec Guiness
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