.NET Framework Class Library
DefaultEventAttribute Class

Specifies the default event for a component.

Inheritance Hierarchy

Namespace:   System.ComponentModel
Assembly:  System (in System.dll)
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Public NotInheritable Class DefaultEventAttribute _
	Inherits [%$TOPIC/cdx1c3yt_en-us_VS_110_2_0_0_0_2%]
public sealed class DefaultEventAttribute : [%$TOPIC/cdx1c3yt_en-us_VS_110_2_0_1_0_2%]
public ref class DefaultEventAttribute sealed : public [%$TOPIC/cdx1c3yt_en-us_VS_110_2_0_2_0_2%]
type DefaultEventAttribute =  
        inherit [%$TOPIC/cdx1c3yt_en-us_VS_110_2_0_3_0_3%] 
public final class DefaultEventAttribute extends [%$TOPIC/cdx1c3yt_en-us_VS_110_2_0_4_0_0%]

The DefaultEventAttribute type exposes the following members.

Public method DefaultEventAttributeInitializes a new instance of the DefaultEventAttribute class.
Public property NameGets the name of the default event for the component this attribute is bound to.
Public property TypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
Public method EqualsReturns whether the value of the given object is equal to the current DefaultEventAttribute. (Overrides AttributeEquals(Object).)
Public method GetHashCodeReturns the hash code for this instance. (Overrides AttributeGetHashCode.)
Public method GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method IsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public method MatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public method ToStringReturns a string that represents the current object. (Inherited from Object.)
Public field Static member DefaultSpecifies the default value for the DefaultEventAttribute, which is . This static field is read-only.
Explicit Interface Implementations
Explicit interface implemetation Private method _AttributeGetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeGetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetation Private method _AttributeInvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)

Use the Name property to get the name of the default event.

For more information, see Extending Metadata Using Attributes.


The following example defines a collection class named MyCollection. The class is marked with a DefaultEventAttribute that specifies CollectionChanged as the default event.

<DefaultEvent("CollectionChanged")> _ 
Public Class MyCollection
    Inherits BaseCollection

    Public Event CollectionChanged (ByVal sender As Object, _
        ByVal e As CollectionChangeEventArgs)

    ' Insert additional code. 
End Class 'MyCollection
public class MyCollection : BaseCollection {

    private CollectionChangeEventHandler onCollectionChanged;

    public event CollectionChangeEventHandler CollectionChanged {
       add {
          onCollectionChanged += value;
       remove {
          onCollectionChanged -= value;
    // Insert additional code.
public ref class TestCollection: public BaseCollection
    CollectionChangeEventHandler^ onCollectionChanged;

    event CollectionChangeEventHandler^ CollectionChanged 
        void add(CollectionChangeEventHandler^ eventHandler)
            onCollectionChanged += eventHandler; 

        void remove(CollectionChangeEventHandler^ eventHandler) 
            onCollectionChanged -= eventHandler; 
    // Insert additional code.

The next example creates an instance of MyCollection. Then it gets the attributes for the class, extracts the DefaultEventAttribute, and prints the name of the default event.

Public Shared Function Main() As Integer 
    ' Creates a new collection. 
    Dim myNewCollection As New MyCollection()

    ' Gets the attributes for the collection. 
    Dim attributes As AttributeCollection = TypeDescriptor.GetAttributes(myNewCollection)

    ' Prints the name of the default event by retrieving the 
    ' DefaultEventAttribute from the AttributeCollection.  
    Dim myAttribute As DefaultEventAttribute = _
        CType(attributes(GetType(DefaultEventAttribute)), DefaultEventAttribute)
    Console.WriteLine(("The default event is: " & myAttribute.Name))
    Return 0
End Function 'Main
public static int Main() {
    // Creates a new collection.
    MyCollection myNewCollection = new MyCollection();

    // Gets the attributes for the collection.
    AttributeCollection attributes = TypeDescriptor.GetAttributes(myNewCollection);

    /* Prints the name of the default event by retrieving the 
     * DefaultEventAttribute from the AttributeCollection. */
    DefaultEventAttribute myAttribute = 
    Console.WriteLine("The default event is: " + myAttribute.Name);
    return 0;
int main()
    // Creates a new collection.
    DefaultEventAttributeExample::TestCollection^ newCollection = 
        gcnew DefaultEventAttributeExample::TestCollection;

    // Gets the attributes for the collection.
    AttributeCollection^ attributes = 

    // Prints the name of the default event by retrieving the  
    // DefaultEventAttribute from the AttributeCollection.
    DefaultEventAttribute^ attribute = (DefaultEventAttribute^)
    Console::WriteLine("The default event is: {0}", attribute->Name);
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.