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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Typing in Ada
References: <W_OdnQOcRN70-CDdRVn-ug@comcast.com>
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Date: 2004-06-02T08:19:37+00:00
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>Second, when the answer is that it should be read as "Count at least 100
>Apples," then the following coding "trick" is very useful:
>
>type Required_Apples is range 0..100; -- 1..100 was pretty dodgy too...
>type Apple is range 0..Required_Apples'Base'Last;
>
>That allows software range checking to be omitted at least on the upper bound,
  OTOH, it means you don't know what the actual upper bound is.  More than
once during testing I've gotten something like "Constraint_Error,
offending value = 101".  If you used
type Apple_Count is range 0 .. 100;
type Orange_Count is range 0 .. 101;
then you immediately know the problem is an overflowing apple count, not
an orange count.  An "offending value = 256" would be less informative.