combit List & Label 25 - .NET Online Web Help
Evaluate Event

combit.ListLabel25 Namespace > ListLabel Class : Evaluate Event

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.

Public Event Evaluate As EvaluateHandler
public event EvaluateHandler Evaluate
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.


Internal Callback data.


User-defined parameters.


Used for error description.


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


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


Return value of the External$ function.

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

Platforms: Windows 7 SP1 - Windows 10 Version 1909, Windows Server 2008 R2 - 2019

See Also