Re: Ada202X : alternate syntax for ranged scalars

[Eryndlia Mavourneen <eryndlia@gmail.com>]

On Friday, April 26, 2013 5:10:01 AM UTC-5, Martin wrote:
> The default scalar declarations are 'closed ranges', i.e. include both upper and lower in the valid range.
> 
> Sometimes we would like to specify a 'half open range', e.g. values of degree from 0.0 up to BUT NOT INCLUDING 360.0.
> 
> I'm floating (pun intended) an alternative syntax for specify such ranges (or 'intervals')...
> 
> type Degree is digits 15 range [0.0, 360.0); -- includes 0 but not 360
> 
> The current 'closed ranges' would be:
> type Degree is digits 15 range [0.0, 360.0]; -- includes 0 and 360
> 
> Fully open range, i.e. not include 0.0 or 360.0:
> 
> type Degree is digits 15 range (0.0, 360.0); -- includes neither 0 nor 360
> 
> A 'reverse' half open range, i.e. not include 0.0 but including 360.0:
> 
> Usual rules would apply to the simple expression between the brackets.
> 
> Any thoughts?
> -- Martin

I agree with Peter.  A syntax more closely allied with current syntax might be:

  type Degree is digits 15 range 0.0 .. not 360.0; -- includes 0 but not 360
 
The current 'closed ranges' would be the same as now:
  type Degree is digits 15 range 0.0 .. 360.0; -- includes 0 and 360
 
Fully open range, i.e. not include 0.0 or 360.0:
 
 type Degree is digits 15 range not 0.0 .. not 360.0; -- includes neither 0 nor 360

That said, we must assume that floating point values get translated *exactly*; that is, 360.0 does not get translated to a machine type of 359.999999... or 360.0111111...

-- Eryndlia F. Mavourneen