DefaultEventAttribute Klasse

Definition

public ref class DefaultEventAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Class)]
public sealed class DefaultEventAttribute : Attribute

public sealed class DefaultEventAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Class)>]
type DefaultEventAttribute = class
    inherit Attribute

type DefaultEventAttribute = class
    inherit Attribute

Public NotInheritable Class DefaultEventAttribute
Inherits Attribute

Vererbung

Object

Attribute

DefaultEventAttribute

Attribute

AttributeUsageAttribute

Beispiele

Im folgenden Beispiel wird eine Auflistungsklasse mit dem Namen MyCollectiondefiniert. Die Klasse ist mit einer DefaultEventAttribute Klasse gekennzeichnet, die als Standardereignis angibt CollectionChanged .

[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.
};

[DefaultEvent("CollectionChanged")]
public class MyCollection : BaseCollection
{
    CollectionChangeEventHandler onCollectionChanged;

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

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

    Public Event CollectionChanged (ByVal sender As Object, _
        ByVal e As CollectionChangeEventArgs)
    
    ' Insert additional code.
End Class

Im nächsten Beispiel wird eine Instanz von MyCollection. Anschließend werden die Attribute für die Klasse extrahiert DefaultEventAttributeund der Name des Standardereignisses gedruckt.

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);
}

public static int Main()
{
    // Creates a new collection.
    MyCollection myNewCollection = new();

    // 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;
}

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

Hinweise

Verwenden Sie die Name Eigenschaft, um den Namen des Standardereignisses abzurufen.

Weitere Informationen finden Sie unter Attribute.

Weitere Informationen

• Attribute