unable to evaluate Custom function with parameterized input

[ibt1haj]

i have implemented my own function to work with the expressions in ncalc

public static async Task<object> EvaluateCustomMathFunction(Expression exp)
 {
     

     exp.EvaluateFunctionAsync += async (name, args) =>
     {
         if (name == Constants.Pos)
         {
             var tempResult = Convert.ToDouble(await args.Parameters[0].EvaluateAsync());
             args.Result = tempResult > 0 ? tempResult : 0;
         }
     };

     var evaluationResult = await exp.EvaluateAsync();
     return evaluationResult;
 }

it works fine for simple inputs like

[Test]
public async Task EvaluateCustomMathFunction_NegativeNumber()
{
    
    var exp = new Expression("Pos(-5)"); 

    
    var result = await CustomExpressionEvaluation.EvaluateCustomMathFunction(exp);

    Assert.That(result, Is.EqualTo(0)); // The method should return 0 for negative input
}

but if i use parametrized input

  [Test]
 public async Task EvaluateCustomMathFunction_WithParameters()
 {
     // Arrange
     var exp = new Expression("Pos(A)", EvaluateOptions.IterateParameters);
     exp.Parameters["A"] = new int[] { 5, 10, -5, 10 };

     // Act
     var result = (IEnumerable) await CustomExpressionEvaluation.EvaluateCustomMathFunction(exp);

     // Assert
     Assert.IsAssignableFrom<IEnumerable>(result);
 }

my function fails to evaluate the expression correctly and throws the exception because the input is now in list

so i have changed my implementation of the custom function

    public static async Task<object> EvaluateCustomMathFunction(Expression exp)
    {

        exp.EvaluateFunctionAsync += async (name, args) =>
        {
            if (name == Constants.Pos)
            {
                var res = await args.EvaluateParametersAsync();
                var tempResult = await args.Parameters[0].EvaluateAsync();

                if (tempResult is IEnumerable<object> list)
                {
                    args.Result = list.Select(x => Convert.ToDouble(x) > 0 ? x : 0);
                }
                else
                {
                    var doubleResult = Convert.ToDouble(tempResult);
                    args.Result = doubleResult > 0 ? doubleResult : 0;
                }
            }
        };
        var evaluationResult = await exp.EvaluateAsync();
        return evaluationResult;
    }

but still it returns '0' for every input parameter value on the following line

var tempResult = await args.Parameters[0].EvaluateAsync();

can some body point me in the right direction ?

[yallie]

Hi @ibt1haj, see my answer here: #23

And working example here: https://dotnetfiddle.net/fToXRw

TL/DR: don't use EvaluateOptions.IterateParameters, I think it's broken and should be reimplemented.