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typesadagnat

Is there a way to disable arithmetic operators on a specific type in Ada?

I would like to define HTML response status code numbers as a type but disallow arithmetic operators because it wouldn't make sense for them.

type Status_Code is range 100 .. 599;

function "+" (Left, Right : Status_Code) return Status_Code is
begin
      pragma Assert (1 = -1);
      return Left + Right;
end;

The code snippet above on GNAT will give an error saying assertion will fail on runtime, but that is false when I add two of the numbers together. Is there a way to force a compiler error or at least a warning when arithmetic attempted on a type like this?

Solution

  • You can declare it as abstract:

    function "+" (Left, Right : Status_Code) return Status_Code is abstract;