ClassInterfaceType Enum

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.InteropServices.dll

Identifies the type of class interface that is generated for a class.

public enum class ClassInterfaceType

public enum ClassInterfaceType

type ClassInterfaceType = 

Public Enum ClassInterfaceType

Inheritance

Object

ValueType

Enum

ClassInterfaceType

Fields

Name	Value	Description
None	0	Indicates that no class interface is generated for the class. If no interfaces are implemented explicitly, the class can only provide late-bound access through the IDispatch interface. This is the recommended setting for ClassInterfaceAttribute. Using ClassInterfaceType.None is the only way to expose functionality through interfaces implemented explicitly by the class. Tlbexp.exe (Type Library Exporter) exposes the first public, COM-visible interface implemented by the class as the default interface of the coclass. In .NET Framework 2.0 and later versions, you can specify the default interface exposed to COM by using the ComDefaultInterfaceAttribute attribute. If the class implements no interfaces, the first public, COM-visible interface implemented by a base class becomes the default interface (starting with the most recently derived base class and working backward). Tlbexp.exe exposes _Object as the default interface if neither the class nor its base classes implement interfaces.
AutoDispatch	1	Indicates that the class only supports late binding for COM clients. A dispinterface for the class is automatically exposed to COM clients on request. The type library produced by Tlbexp.exe (Type Library Exporter) does not contain type information for the dispinterface in order to prevent clients from caching the DISPIDs of the interface. The dispinterface does not exhibit the versioning problems described in ClassInterfaceAttribute because clients can only late-bind to the interface. This is the default setting for ClassInterfaceAttribute.
AutoDual	2	Indicates that a dual class interface is automatically generated for the class and exposed to COM. Type information is produced for the class interface and published in the type library. Using AutoDual is strongly discouraged because of the versioning limitations described in ClassInterfaceAttribute.

Examples

This example shows how to apply the ClassInterfaceAttribute to a type, setting the ClassInterfaceType. Classes defined this way can be used from unmanaged COM.

using namespace System;
using namespace System::Runtime::InteropServices;

// Have the CLR expose a class interface (derived from IDispatch)
// for this type. COM clients can call the  members of this
// class using the Invoke method from the IDispatch interface.
[ClassInterface(ClassInterfaceType::AutoDispatch)]
public ref class AClassUsableViaCOM
{
public:
    AClassUsableViaCOM() 
    { 
    }

public:
    int Add(int x, int y)
    {
        return x + y;
    }
};

// The CLR does not expose a class interface for this type.
// COM clients can call the members of this class using
// the methods from the IComparable interface.
[ClassInterface(ClassInterfaceType::None)]
public ref class AnotherClassUsableViaCOM : public IComparable
{
public:
    AnotherClassUsableViaCOM() 
    { 
    }

    virtual int CompareTo(Object^ o) = IComparable::CompareTo
    {
        return 0;
    }
};

using System;
using System.Runtime.InteropServices;

// Have the CLR expose a class interface (derived from IDispatch) for this type.
// COM clients can call the  members of this class using the Invoke method from the IDispatch interface.
[ClassInterface(ClassInterfaceType.AutoDispatch)]
public class AClassUsableViaCOM
{
    public AClassUsableViaCOM() { }

    public Int32 Add(Int32 x, Int32 y) { return x + y; }
}

// The CLR does not expose a class interface for this type.
// COM clients can call the members of this class using the methods from the IComparable interface.
[ClassInterface(ClassInterfaceType.None)]
public class AnotherClassUsableViaCOM : IComparable
{
    public AnotherClassUsableViaCOM() { }

    Int32 IComparable.CompareTo(Object o) { return 0; }
}

Imports System.Runtime.InteropServices


' Have the CLR expose a class interface (derived from IDispatch) for this type.
' COM clients can call the  members of this class using the Invoke method from the IDispatch interface.
<ClassInterface(ClassInterfaceType.AutoDispatch)> _
Public Class AClassUsableViaCOM

    Public Sub New()

    End Sub

    Public Function Add(ByVal x As Int32, ByVal y As Int32) As Int32
        Return x + y

    End Function
End Class
' The CLR does not expose a class interface for this type.
' COM clients can call the members of this class using the methods from the IComparable interface.
<ClassInterface(ClassInterfaceType.None)> _
Public Class AnotherClassUsableViaCOM
    Implements IComparable

    Public Sub New()

    End Sub

    Function CompareTo(ByVal o As [Object]) As Int32 Implements IComparable.CompareTo
        Return 0

    End Function 'IComparable.CompareTo
End Class

Remarks

This enumeration is used in conjunction with the ClassInterfaceAttribute attribute.

See also

• Tlbexp.exe (Type Library Exporter)