List & Label .NET
combit.Reporting Namespace / ListLabel Class / Evaluate Event


In This Topic
    Evaluate Event
    In This Topic

    The Designer function External$ allows offering of external functions in the List & Label formula assistant. Whenever the user uses this function, the Evaluate event is called, which evaluates the formula and returns the result or an error message. Usually it is preferable to use the DesignerFunction Class for custom functions.

    Syntax
    'Declaration
 

    Public Event Evaluate As EvaluateHandler
    public event EvaluateHandler Evaluate
    public:
event EvaluateHandler^ Evaluate
    Event Data

    The event handler receives an argument of type EvaluateEventArgs containing data related to this event. The following EvaluateEventArgs properties provide information specific to this event.

    PropertyDescription
    CallbackData

    Internal Callback data.

     
    Contents

    User-defined parameters.

     
    ErrorText

    Used for error description.

     
    Evaluate

    Indicates whether the function is to be evaluated or checked only for syntax.

     
    HasError

    Indicates that an error was encountered at the time of evaluation.

     
    NewValue

    Return value of the External$ function.

     
    Example
    private void LL_Evaluate(object sender, EvaluateEventArgs e)
{
     if(e.Contents == "greeting")
     {
          e.NewValue = "Hello World";
     }
     else
     {
          e.HasError = true;
          e.ErrorText = "You must enter \"greeting\".";
     }
}
    Requirements

    Platforms: Windows 10 (Version 21H2 - 22H2), Windows 11 (22H2 - 25H2), Windows Server 2016 - 2025
    .NET: .NET Framework 4.8, .NET 8, .NET 9, .NET 10

    See Also

    Reference

    ListLabel Class
    ListLabel Members

     

     

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