ICustomFunction Interface

Defines properties and methods required to implement your own worksheet function.

Namespace: DevExpress.Spreadsheet.Functions

Assembly: DevExpress.Spreadsheet.v17.2.Core.dll

Declaration

C#

public interface ICustomFunction :
    IFunction

VB.NET

Public Interface ICustomFunction
    Inherits IFunction

Related API Members

The following members accept/return ICustomFunction objects:

• CustomFunctionCollection.Item[String]

Remarks

Note

A complete sample project is available at https://github.com/DevExpress-Examples/winforms-spreadsheetcontrol-api-part-2-e4832

CustomFunctionActions.cs

using DevExpress.Spreadsheet;
using DevExpress.Spreadsheet.Functions;
using DevExpress.XtraSpreadsheet;
// Create a custom function and add it to the global scope.
SphereMassFunction customFunction = new SphereMassFunction();
if (!workbook.Functions.GlobalCustomFunctions.Contains(customFunction.Name))
    workbook.Functions.GlobalCustomFunctions.Add(customFunction);
public class SphereMassFunction : ICustomFunction
{
    const string functionName = "SPHEREMASS";
    readonly ParameterInfo[] functionParameters;

    public SphereMassFunction()
    {   
        // Missing optional parameters do not result in an error message.
        this.functionParameters = new ParameterInfo[] { new ParameterInfo(ParameterType.Value, ParameterAttributes.Required), 
            new ParameterInfo(ParameterType.Value, ParameterAttributes.Optional)};
    }

    public string Name { get { return functionName; } }
    ParameterInfo[] IFunction.Parameters { get { return functionParameters; } }
    ParameterType IFunction.ReturnType { get { return ParameterType.Value; } }
    bool IFunction.Volatile { get { return false; } }

    ParameterValue IFunction.Evaluate(IList<ParameterValue> parameters, EvaluationContext context)
    {
        double radius;
        double density = 1000;
        ParameterValue radiusParameter;
        ParameterValue densityParameter;

        if (parameters.Count == 2)
        {
            densityParameter = parameters[1];
            if (densityParameter.IsError)
                return densityParameter;
            else 
                density = densityParameter.NumericValue;                
        }

        radiusParameter = parameters[0];
        if (radiusParameter.IsError)
            return radiusParameter;
        else
            radius = radiusParameter.NumericValue;

        return (4 * Math.PI) / 3 * Math.Pow(radius,3) * density;

    }
    string IFunction.GetName(CultureInfo culture)
    {
        return functionName;
    }
}

CustomFunctionActions.vb

Imports DevExpress.Spreadsheet
Imports DevExpress.Spreadsheet.Functions
Imports DevExpress.XtraSpreadsheet
' Create a custom function and add it to the global scope.
Dim customFunction As New SphereMassFunction()
If Not workbook.Functions.GlobalCustomFunctions.Contains(customFunction.Name) Then
    workbook.Functions.GlobalCustomFunctions.Add(customFunction)
End If
' Inheritance from Object is required for automatic VB.NET conversion
Public Class SphereMassFunction
        Implements  ICustomFunction

    Private Const functionName As String = "SPHEREMASS"
    Private ReadOnly functionParameters() As ParameterInfo

    Public Sub New()
        ' Missing optional parameters do not result in an error message.
        Me.functionParameters = New ParameterInfo() {
            New ParameterInfo(ParameterType.Value, ParameterAttributes.Required),
            New ParameterInfo(ParameterType.Value, ParameterAttributes.Optional)
        }
    End Sub

    Public ReadOnly Property Name() As String Implements IFunction.Name
        Get
            Return functionName
        End Get
    End Property
    Private ReadOnly Property IFunction_Parameters() As ParameterInfo() Implements IFunction.Parameters
        Get
            Return functionParameters
        End Get
    End Property
    Private ReadOnly Property IFunction_ReturnType() As ParameterType Implements IFunction.ReturnType
        Get
            Return ParameterType.Value
        End Get
    End Property
    Private ReadOnly Property IFunction_Volatile() As Boolean Implements IFunction.Volatile
        Get
            Return False
        End Get
    End Property

    Private Function IFunction_Evaluate(ByVal parameters As IList(Of ParameterValue), ByVal context As EvaluationContext) As ParameterValue Implements IFunction.Evaluate
        Dim radius As Double
        Dim density As Double = 1000
        Dim radiusParameter As ParameterValue
        Dim densityParameter As ParameterValue

        If parameters.Count = 2 Then
            densityParameter = parameters(1)
            If densityParameter.IsError Then
                Return densityParameter
            Else
                density = densityParameter.NumericValue
            End If
        End If

        radiusParameter = parameters(0)
        If radiusParameter.IsError Then
            Return radiusParameter
        Else
            radius = radiusParameter.NumericValue
        End If

        Return (4 * Math.PI) / 3 * Math.Pow(radius,3) * density

    End Function
    Private Function IFunction_GetName(ByVal culture As CultureInfo) As String Implements IFunction.GetName
        Return functionName
    End Function
End Class

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the ICustomFunction interface.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

how-to-use-excel-add-ins-in-the-spreadsheet-control-e5012/CS/SpreadsheetAddIn/Form1.cs#L60

public class AddInFunction : ICustomFunction
{

udf-custom-function-how-to-replace-excel-xll-add-in-udf-with-a-custom-function-e5178/CS/UDF_Discount/DiscountFunction.cs#L12

// Inheritance from Object is required for correct automatic VB.NET conversion
public class DiscountFunction : Object, ICustomFunction
{

wpf-spreadsheetcontrol-api-part-2-e4944/CS/SpreadsheetControl_WPF_API_Part02/SpreadsheetActions/CustomFunctionActions.cs#L70

// Inheritance from Object is required for correct automatic VB.NET conversion
public class SphereMassFunction : Object, ICustomFunction
{

winforms-spreadsheetcontrol-api-part-2-e4832/CS/SpreadsheetControl_API_Part02/SpreadsheetActions/CustomFunctionActions.cs#L73

#region #customfunctiondef
public class SphereMassFunction : ICustomFunction
{

udf-custom-function-a-sample-custom-function-that-returns-an-array-t538369/CS/CustomFunctionReturningArrayExample/TestArrayCustomFunction.cs#L12

#region #TestArrayCustomFunctionImplement
public class TestArrayCustomFunction : ICustomFunction {
    private string name = "TESTARRAY";

VB.NET

udf-custom-function-a-sample-custom-function-that-returns-an-array-t538770/VB/CustomFunctionReturningArrayExample/TestArrayCustomFunction.vb#L9

Public Class TestArrayCustomFunction
    Implements ICustomFunction
    Private name_Renamed As String = "TESTARRAY"

udf-custom-function-a-sample-custom-function-that-returns-an-array-t538369/VB/CustomFunctionReturningArrayExample/TestArrayCustomFunction.vb#L13

Public Class TestArrayCustomFunction
    Implements ICustomFunction

udf-custom-function-how-to-replace-excel-xll-add-in-udf-with-a-custom-function-e5178/VB/UDF_Discount/DiscountFunction.vb#L14

Inherits Object
Implements ICustomFunction
Private Const functionName As String = "Discount"

wpf-spreadsheetcontrol-api-part-2-e4944/VB/SpreadsheetControl_WPF_API_Part02/SpreadsheetActions/CustomFunctionActions.vb#L71

Inherits Object
Implements ICustomFunction

how-to-use-excel-add-ins-in-the-spreadsheet-control-e5012/VB/SpreadsheetAddIn/Form1.vb#L57

Public Class AddInFunction
    Implements ICustomFunction