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.NET Framework Class Library
DefaultEventAttribute Class

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Specifies the default event for a component.

System..::.Object
  System..::.Attribute
    System.ComponentModel..::.DefaultEventAttribute

Namespace:  System.ComponentModel
Assembly:  System (in System.dll)
Visual Basic
<AttributeUsageAttribute(AttributeTargets.Class)> _
Public NotInheritable Class DefaultEventAttribute _
	Inherits Attribute
C#
[AttributeUsageAttribute(AttributeTargets.Class)]
public sealed class DefaultEventAttribute : Attribute
Visual C++
[AttributeUsageAttribute(AttributeTargets::Class)]
public ref class DefaultEventAttribute sealed : public Attribute
F#
[<Sealed>]
[<AttributeUsageAttribute(AttributeTargets.Class)>]
type DefaultEventAttribute =  
    class
        inherit Attribute
    end

The DefaultEventAttribute type exposes the following members.

  NameDescription
Public methodDefaultEventAttributeInitializes a new instance of the DefaultEventAttribute class.
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  NameDescription
Public propertyNameGets the name of the default event for the component this attribute is bound to.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsReturns whether the value of the given object is equal to the current DefaultEventAttribute. (Overrides Attribute..::.Equals(Object).)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeReturns the hash code for this instance. (Overrides Attribute..::.GetHashCode()()().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberDefaultSpecifies the default value for the DefaultEventAttribute, which is nullNothingnullptra null reference (Nothing in Visual Basic). This static field is read-only.
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  NameDescription
Explicit interface implemetationPrivate method_Attribute..::.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute..::.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute..::.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute..::.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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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.

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

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

    ' Insert additional code.
End Class 'MyCollection

C#
[DefaultEvent("CollectionChanged")]
public class MyCollection : BaseCollection {

    private CollectionChangeEventHandler onCollectionChanged;

    public event CollectionChangeEventHandler CollectionChanged {
       add {
          onCollectionChanged += value;
       }
       remove {
          onCollectionChanged -= value;
       }
    }
    // Insert additional code.
}

Visual C++
[DefaultEvent("CollectionChanged")]
public ref class TestCollection: public BaseCollection
{
private:
    CollectionChangeEventHandler^ onCollectionChanged;

public:
    event CollectionChangeEventHandler^ CollectionChanged 
    {
    public:
        void add(CollectionChangeEventHandler^ eventHandler)
        { 
            onCollectionChanged += eventHandler; 
        }

    protected:
        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.

Visual Basic
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

C#
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 = 
       (DefaultEventAttribute)attributes[typeof(DefaultEventAttribute)];
    Console.WriteLine("The default event is: " + myAttribute.Name);
    return 0;
 }

Visual C++
int main()
{
    // Creates a new collection.
    DefaultEventAttributeExample::TestCollection^ newCollection = 
        gcnew DefaultEventAttributeExample::TestCollection;

    // Gets the attributes for the collection.
    AttributeCollection^ attributes = 
        TypeDescriptor::GetAttributes(newCollection);

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

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8 Consumer Preview, Windows Server 8 Beta, Windows 7, Windows Server 2008 SP2, Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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