Re: How to best make a custom range?

[Shark8 <onewingedshark@gmail.com>]

On Monday, November 4, 2019 at 10:26:22 AM UTC-7, Andrew Shvets wrote:
> Lets say I have the following code:
> 
> subtype Test_Char is Character range ‘A’ .. ‘Z’;
> 
> But what if I wanted to include ‘&’, ‘@‘ and ‘?’ in this custom range of characters as well?  I thought of doing the following, but this obviously failed:
> 
> subtype Test_Char is Character range ‘@‘ | ‘&’ | ‘?’ | ‘A’ .. ‘Z’;
> 
> Or is this impossible unless I use a different approach?


The approach I've been going with is splitting things apart into parts:

  Subtype Upper  is Character range 'A'..'Z';
  Subtype Lower  is Character range 'a'..'z';
  Subtype Symbol is Character
    with Static_Predicate => '&' | '@' | '?';

  Subtype Test_Character is Character
    with Static_Predicate => Upper | Lower | Symbol;