replaceCallBy

ReplaceCallBy.cyan

package metaobjectTest


@doc{*
  Annotation 'replaceCallBy' should be attached to a final method. It
  replaces any message passings to the method by the attached DSL code.
  The DSL code may use the parameters, which are re-calculated if
  parameter 'once' to the annotation is not used.
  
  All methods of the prototype ReplaceCallBy are final because it is a
  final prototype.
*}
object ReplaceCallBy

    func run {
        var value = threeTimes: 3;
        assert value == 9;    
        value = threeTimes: next;
        assert value == 3;
        
        nextValue = 0;
        value = threeTimesOnce: 3;
        assert value == 9;        

        nextValue = 0;
        // value = 1 + 1 + 1
        value = threeTimesOnce: next;
        assert value == 3;    
        
    }
    
    @replaceCallBy{*  3*n  *}
    func threeTimes: Int n -> Int = n;
    
    
    @replaceCallBy(once){*  n + n + n  *}
    func threeTimesOnce: Int n -> Int = n;


    func next -> Int { ++nextValue; return nextValue; }
    
    var Int nextValue = 0;
end