Re: Ada2005 random

[Lutz Donnerhacke <lutz@iks-jena.de>]

* Peter Hermann wrote:
> Lutz and all,
>> * Peter Hermann wrote:
>>> In an application I need a variable discrete random function.
>                               ^^^^^^^^
> with "variable" I meant the following flexibility,  e.g. :
>                   a := random(generator1, 1 , 9);
>                   b := random(generator1, 1 , 8);
>                   c := random(generator1, 3 , 7);

procedure random(g : in out Generator; min, max : X; rand : out X)
  --# derives rand from g, min, max and
  --#            g from g;
  --# pre max > min;
  --# post rand in min .. max;
  is
   absmax : X;
begin
   absmax := X'Last - (X'Last - X'First) mod (max - min);
   --# check absmax > X'First;
   loop
      random(g, rand); --  ... random (g : in out Generator; r : out X) ...
      exit when rand <= absmax;
   end loop;
   return (rand - X'First) mod (max - min) + min;
end random;

Ok, it's the C approach ;-)