Re: New limited range type?

[Larry Hazel <lhhazel@otelco.net>]

Martin Dowie wrote:
> "Hyman Rosen" <hyrosen@mail.com> wrote in message
> news:1068224385.790621@master.nyc.kbcfp.com...
> 
>>Martin Dowie wrote:
>>
>>>Standard operator precedent rules should apply - I can't see
>>>that as being outragous?
>>
>>But Ada doesn't define operator evaluation order, so this would
>>be a major change in the language. (Not a bad one, just big.)
> 
> 
> Well it 'kind of' does in that the order must be "an allowed result
> for the left-to-right association".
> 
> You could argue that the case "A := B + C - D," for these 'limited
> range' types _can_only_ be equivilent to "A := (B + C) - D;".
> 
> 
> 
An analog computer implements saturating arithmetic.  Oh my God, how 
long has it been since anyone saw an analog computer.  The sum B + C - D 
would be computed all at once and would only saturate if the final 
result was out of range.  So, I think the expression should be evaluated 
in a base type with saturation applied to the result.