The feature such as How to adjust the priority of function parameters?

[wqmeng]

Let' say I have a function which has 2 parameters. Ex:

// find the max value from the last period values from the range from Length - 1 - period to Length - 1;
function _FindMaxofLastValues(const AValues: array of Double; const APeriod: Integer): Double;
var
  I, Len: Integer;
begin
  Len := Length(AValues);
  Result := -MaxDouble;
  for I:= Len - 1 downto Max(0, Len - 1 - APeriod) do begin
      if Result < AValues[I] then
        Result := AValues[I];
  end;
end;

Then add procedure dwsUnitFindMaxofLastValues_Eval(Info: TProgramInfo) to call the above _FindMaxofLastValues function.

Then register this function to DWScript.

    fn := Self.FdwsUnit.Functions.Add;
    fn.Name := 'FindMaxofLastValues';
    fn.ResultType := 'Float';
    fn.Overloaded := true;
    fn.OnEval := dwsUnitFindMaxofLastValues_Eval;
    P1 := fn.Parameters.Add('Values', 'Array of Float');  // float array
    P2 := fn.Parameters.Add('Period', 'Integer');
    // Inc(P2.priority);  // Let set default priority is zero, and priority bigger will run firstly.?   
    // + P2 priority here and let it run before P1 <==========

Until now everthing should works well, but the performance.

The problem is the first parameter should return a array, But it does not know the length that it should return, so it will return all the array.

Such as in DWScript

'''
var
  A, B: array of Float;
A := [1, 2, 3, 4, 5];
B := [5, 5, 5, 5, 0];

FindMaxofLastValues(ArrayValueAdd(A, B),  2);    // In ArrayValueAdd,  A values will add B values and return [6, 7, 8, 9, 5];
'''

In the above script, If we could let the ArrayValueAdd know the period 2, then it could only return the result array of [9, 5].

So here I would like to change the run order of the param by change the priority of a parameter.

And there still need another feature such as OnAfterEval event of the paramter, And call back the OnAfterEval functino to change the Context to effect the P1 to only return a array of length Period value.

I checked some code and couldn't find these functions in the DWScript source code. So can we accomplish this?

Thank you very much.