Re: Typing in Ada

[Wes Groleau <groleau+news@freeshell.org>]

Niklas Holsti wrote:
> To return to Nick Robert's example, the numbers 100 and 200 should 
> either come from the requirements specification ("The program shall be 
> able to count  up to 100 apples and 200 oranges...") or should appear in 
> the software user manual ("The program can count up to 100 apples and 
> 200 oranges"). So then it is clear that the program satisfies its 
> requirements (or it won't compile) and satisfies its user manual, 
> whatever range Standard.Integer has on the current platform.

In a way, you are correct.  But why must we put
so much effort into preventing behavior that is
not prohibited just because it is not required?

Does the specification say ... ?
   "The program shall not tolerate apple counts higher than 100"

Did some domain expert persuade the programmers that 101 apples
was not reasonable?

In other words, when a specification says
"A count of 100 must be supported,"  the
programmers should NOT mentally rewrite it
to "Counts larger than 100 must not be supported."

-- 
Wes Groleau
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