restrict the values a variable can hold

RestrictTo

package metaobjectTest


@doc{*
  Annotation 'type' should be attached to a type. It checks whether
  the value of the type obeys the expression that is attached to 
  the annotation
*}
object RestrictTo

    func run {
        var Int@restrictTo{* self >= 0 *} age;
        age = 0;
        age = 10;
        var ok = false;
        { 
            age = -1;
        } catch: { (: CyException e :) 
             ok = true
        };
        assert ok;
    
    }

end