MulticastDelegate Classe
Definição
Importante
Algumas informações se referem a produtos de pré-lançamento que podem ser substancialmente modificados antes do lançamento. A Microsoft não oferece garantias, expressas ou implícitas, das informações aqui fornecidas.
Representa um delegado multicast; ou seja, um delegado que pode ter mais de um elemento em sua lista de invocação.
public ref class MulticastDelegate abstract : Delegate
public abstract class MulticastDelegate : Delegate
[System.Serializable]
public abstract class MulticastDelegate : Delegate
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class MulticastDelegate : Delegate
type MulticastDelegate = class
inherit Delegate
[<System.Serializable>]
type MulticastDelegate = class
inherit Delegate
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type MulticastDelegate = class
inherit Delegate
Public MustInherit Class MulticastDelegate
Inherits Delegate
- Herança
- Atributos
Exemplos
O exemplo a seguir define uma classe, StringContainer
, que inclui uma coleção de cadeias de caracteres. Um de seus membros é o delegado CheckAndDisplayDelegate
, que é usado para exibir cadeias de caracteres armazenadas em um objeto StringContainer
que atendam a critérios específicos. O delegado usa uma única cadeia de caracteres como um parâmetro e retorna void
(ou, no Visual Basic, é um procedimento Sub
). Ele também inclui um método, DisplayAllQualified
, que tem um único parâmetro, um delegado de CheckAndDisplayDelegate
. Isso permite que o método seja chamado e exiba um conjunto de cadeias de caracteres filtradas com base nos métodos que o delegado contém.
O exemplo também define uma classe de utilitário, StringExtensions
, que tem dois métodos:
ConStart
, que exibe cadeias de caracteres que começam com uma consoante.VowelStart
, que exibe cadeias de caracteres que começam com uma vogal.
Observe que ambos os métodos incluem um único parâmetro de cadeia de caracteres e retornam void
. Em outras palavras, ambos os métodos podem ser atribuídos ao delegado CheckAndDisplayDelegate
.
O método Test.Main
é o ponto de entrada do aplicativo. Ele cria uma instância de um objeto StringContainer
, preenche-o com cadeias de caracteres e cria dois delegados CheckAndDisplayDelegate
, conStart
e vowelStart
, que invocam um único método. Em seguida, ele chama o método Delegate.Combine para criar o delegado multipleDelegates
, que inicialmente contém os delegados ConStart
e VowelStart
. Observe que, quando o delegado multipleDelegates
é invocado, ele exibe todas as cadeias de caracteres na coleção em sua ordem original. Isso ocorre porque cada carta é passada separadamente para cada delegado e cada carta atende aos critérios de filtragem de apenas um dos dois delegados. Por fim, após chamadas para Delegate.Remove e Delegate.Combine, multipleDelegates
contém dois delegados conStart
. Quando ele é invocado, cada cadeia de caracteres no objeto StringContainer
é exibida duas vezes.
using namespace System;
using namespace System::Collections::Generic;
ref class StringContainer
{
private:
// A generic list object that holds the strings.
List<String^>^ container = gcnew List<String^>;
public:
// Define a delegate to handle string display.
delegate void CheckAndDisplayDelegate(String^ str);
// A method that adds more strings to the collection.
void AddString(String^ str)
{
container->Add(str);
}
// Iterate through the strings and invoke the method(s) that the delegate points to.
void DisplayAllQualified(CheckAndDisplayDelegate^ displayDelegate)
{
for each (String^ str in container)
displayDelegate(str);
// System::Collections::IEnumerator^ myEnum = container->GetEnumerator();
// while ( myEnum->MoveNext() )
// {
// String^ str = safe_cast<String^>(myEnum->Current);
// displayDelegate(str);
// }
}
};
//end of class StringContainer
// This class contains a few sample methods
ref class StringFuncs
{
public:
// This method prints a String* that it is passed if the String* starts with a vowel
static void ConStart(String^ str)
{
if ( !(str[ 0 ] == 'a' || str[ 0 ] == 'e' || str[ 0 ] == 'i' || str[ 0 ] == 'o' || str[ 0 ] == 'u') )
Console::WriteLine( str );
}
// This method prints a String* that it is passed if the String* starts with a consonant
static void VowelStart( String^ str )
{
if ( (str[ 0 ] == 'a' || str[ 0 ] == 'e' || str[ 0 ] == 'i' || str[ 0 ] == 'o' || str[ 0 ] == 'u') )
Console::WriteLine( str );
}
};
// This function demonstrates using Delegates, including using the Remove and
// Combine methods to create and modify delegate combinations.
int main()
{
// Declare the StringContainer class and add some strings
StringContainer^ container = gcnew StringContainer;
container->AddString( "This" );
container->AddString( "is" );
container->AddString( "a" );
container->AddString( "multicast" );
container->AddString( "delegate" );
container->AddString( "example" );
// RETURN HERE.
// Create two delegates individually using different methods
StringContainer::CheckAndDisplayDelegate^ conStart = gcnew StringContainer::CheckAndDisplayDelegate( StringFuncs::ConStart );
StringContainer::CheckAndDisplayDelegate^ vowelStart = gcnew StringContainer::CheckAndDisplayDelegate( StringFuncs::VowelStart );
// Get the list of all delegates assigned to this MulticastDelegate instance.
array<Delegate^>^ delegateList = conStart->GetInvocationList();
Console::WriteLine("conStart contains {0} delegate(s).", delegateList->Length);
delegateList = vowelStart->GetInvocationList();
Console::WriteLine("vowelStart contains {0} delegate(s).\n", delegateList->Length );
// Determine whether the delegates are System::Multicast delegates
if ( dynamic_cast<System::MulticastDelegate^>(conStart) && dynamic_cast<System::MulticastDelegate^>(vowelStart) )
{
Console::WriteLine("conStart and vowelStart are derived from MulticastDelegate.\n");
}
// Execute the two delegates.
Console::WriteLine("Executing the conStart delegate:" );
container->DisplayAllQualified(conStart);
Console::WriteLine();
Console::WriteLine("Executing the vowelStart delegate:" );
container->DisplayAllQualified(vowelStart);
// Create a new MulticastDelegate and call Combine to add two delegates.
StringContainer::CheckAndDisplayDelegate^ multipleDelegates =
dynamic_cast<StringContainer::CheckAndDisplayDelegate^>(Delegate::Combine(conStart, vowelStart));
// How many delegates does multipleDelegates contain?
delegateList = multipleDelegates->GetInvocationList();
Console::WriteLine("\nmultipleDelegates contains {0} delegates.\n",
delegateList->Length );
// // Pass this multicast delegate to DisplayAllQualified.
Console::WriteLine("Executing the multipleDelegate delegate.");
container->DisplayAllQualified(multipleDelegates);
// Call remove and combine to change the contained delegates.
multipleDelegates = dynamic_cast<StringContainer::CheckAndDisplayDelegate^>
(Delegate::Remove(multipleDelegates, vowelStart));
multipleDelegates = dynamic_cast<StringContainer::CheckAndDisplayDelegate^>
(Delegate::Combine(multipleDelegates, conStart));
// Pass multipleDelegates to DisplayAllQualified again.
Console::WriteLine("\nExecuting the multipleDelegate delegate with two conStart delegates:");
container->DisplayAllQualified(multipleDelegates);
}
// The example displays the following output:
// conStart contains 1 delegate(s).
// vowelStart contains 1 delegate(s).
//
// conStart and vowelStart are derived from MulticastDelegate.
//
// Executing the conStart delegate:
// This
// multicast
// delegate
//
// Executing the vowelStart delegate:
// is
// a
// example
//
//
// multipleDelegates contains 2 delegates.
//
// Executing the multipleDelegate delegate.
// This
// is
// a
// multicast
// delegate
// example
//
// Executing the multipleDelegate delegate with two conStart delegates:
// This
// This
// multicast
// multicast
// delegate
// delegate
using System;
using System.Collections.Generic;
class StringContainer
{
// Define a delegate to handle string display.
public delegate void CheckAndDisplayDelegate(string str);
// A generic list object that holds the strings.
private List<String> container = new List<String>();
// A method that adds strings to the collection.
public void AddString(string str)
{
container.Add(str);
}
// Iterate through the strings and invoke the method(s) that the delegate points to.
public void DisplayAllQualified(CheckAndDisplayDelegate displayDelegate)
{
foreach (var str in container) {
displayDelegate(str);
}
}
}
// This class defines some methods to display strings.
class StringExtensions
{
// Display a string if it starts with a consonant.
public static void ConStart(string str)
{
if (!(str[0]=='a'||str[0]=='e'||str[0]=='i'||str[0]=='o'||str[0]=='u'))
Console.WriteLine(str);
}
// Display a string if it starts with a vowel.
public static void VowelStart(string str)
{
if ((str[0]=='a'||str[0]=='e'||str[0]=='i'||str[0]=='o'||str[0]=='u'))
Console.WriteLine(str);
}
}
// Demonstrate the use of delegates, including the Remove and
// Combine methods to create and modify delegate combinations.
class Test
{
static public void Main()
{
// Declare the StringContainer class and add some strings
StringContainer container = new StringContainer();
container.AddString("This");
container.AddString("is");
container.AddString("a");
container.AddString("multicast");
container.AddString("delegate");
container.AddString("example");
// Create two delegates individually using different methods.
StringContainer.CheckAndDisplayDelegate conStart = StringExtensions.ConStart;
StringContainer.CheckAndDisplayDelegate vowelStart = StringExtensions.VowelStart;
// Get the list of all delegates assigned to this MulticastDelegate instance.
Delegate[] delegateList = conStart.GetInvocationList();
Console.WriteLine("conStart contains {0} delegate(s).", delegateList.Length);
delegateList = vowelStart.GetInvocationList();
Console.WriteLine("vowelStart contains {0} delegate(s).\n", delegateList.Length);
// Determine whether the delegates are System.Multicast delegates.
if (conStart is System.MulticastDelegate && vowelStart is System.MulticastDelegate)
Console.WriteLine("conStart and vowelStart are derived from MulticastDelegate.\n");
// Execute the two delegates.
Console.WriteLine("Executing the conStart delegate:");
container.DisplayAllQualified(conStart);
Console.WriteLine();
Console.WriteLine("Executing the vowelStart delegate:");
container.DisplayAllQualified(vowelStart);
Console.WriteLine();
// Create a new MulticastDelegate and call Combine to add two delegates.
StringContainer.CheckAndDisplayDelegate multipleDelegates =
(StringContainer.CheckAndDisplayDelegate) Delegate.Combine(conStart, vowelStart);
// How many delegates does multipleDelegates contain?
delegateList = multipleDelegates.GetInvocationList();
Console.WriteLine("\nmultipleDelegates contains {0} delegates.\n",
delegateList.Length);
// Pass this multicast delegate to DisplayAllQualified.
Console.WriteLine("Executing the multipleDelegate delegate.");
container.DisplayAllQualified(multipleDelegates);
// Call remove and combine to change the contained delegates.
multipleDelegates = (StringContainer.CheckAndDisplayDelegate) Delegate.Remove(multipleDelegates, vowelStart);
multipleDelegates = (StringContainer.CheckAndDisplayDelegate) Delegate.Combine(multipleDelegates, conStart);
// Pass multipleDelegates to DisplayAllQualified again.
Console.WriteLine("\nExecuting the multipleDelegate delegate with two conStart delegates:");
container.DisplayAllQualified(multipleDelegates);
}
}
// The example displays the following output:
// conStart contains 1 delegate(s).
// vowelStart contains 1 delegate(s).
//
// conStart and vowelStart are derived from MulticastDelegate.
//
// Executing the conStart delegate:
// This
// multicast
// delegate
//
// Executing the vowelStart delegate:
// is
// a
// example
//
//
// multipleDelegates contains 2 delegates.
//
// Executing the multipleDelegate delegate.
// This
// is
// a
// multicast
// delegate
// example
//
// Executing the multipleDelegate delegate with two conStart delegates:
// This
// This
// multicast
// multicast
// delegate
// delegate
module Test
open System
// Define a delegate to handle string display.
type CheckAndDisplayDelegate = delegate of string -> unit
type StringContainer() =
// A generic ResizeArray object that holds the strings.
let container = ResizeArray()
// A method that adds strings to the collection.
member _.AddString(str) =
container.Add str
// Iterate through the strings and invoke the method(s) that the delegate points to.
member _.DisplayAllQualified(displayDelegate: CheckAndDisplayDelegate) =
for str in container do
displayDelegate.Invoke str
// This module defines some functions to display strings.
module StringExtensions =
// Display a string if it starts with a consonant.
let conStart (str: string) =
match str[0] with
| 'a' | 'e' | 'i' | 'o' | 'u' -> ()
| _ -> printfn $"{str}"
// Display a string if it starts with a vowel.
let vowelStart (str: string) =
match str[0] with
| 'a' | 'e' | 'i' | 'o' | 'u' -> printfn $"{str}"
| _ -> ()
// Demonstrate the use of delegates, including the Remove and
// Combine methods to create and modify delegate combinations.
[<EntryPoint>]
let main _ =
// Declare the StringContainer class and add some strings
let container = StringContainer()
container.AddString "This"
container.AddString "is"
container.AddString "a"
container.AddString "multicast"
container.AddString "delegate"
container.AddString "example"
// Create two delegates individually using different methods.
let conStart = CheckAndDisplayDelegate StringExtensions.conStart
let vowelStart = CheckAndDisplayDelegate StringExtensions.vowelStart
// Get the list of all delegates assigned to this MulticastDelegate instance.
let delegateList = conStart.GetInvocationList()
printfn $"conStart contains {delegateList.Length} delegate(s)."
let delegateList = vowelStart.GetInvocationList()
printfn $"vowelStart contains {delegateList.Length} delegate(s).\n"
// Determine whether the delegates are System.Multicast delegates.
if box conStart :? System.MulticastDelegate && box vowelStart :? System.MulticastDelegate then
printfn "conStart and vowelStart are derived from MulticastDelegate.\n"
// Execute the two delegates.
printfn "Executing the conStart delegate:"
container.DisplayAllQualified conStart
printfn "\nExecuting the vowelStart delegate:"
container.DisplayAllQualified vowelStart
printfn ""
// Create a new MulticastDelegate and call Combine to add two delegates.
let multipleDelegates =
Delegate.Combine(conStart, vowelStart) :?> CheckAndDisplayDelegate
// How many delegates does multipleDelegates contain?
let delegateList = multipleDelegates.GetInvocationList()
printfn $"\nmultipleDelegates contains {delegateList.Length} delegates.\n"
// Pass this multicast delegate to DisplayAllQualified.
printfn "Executing the multipleDelegate delegate."
container.DisplayAllQualified multipleDelegates
// Call remove and combine to change the contained delegates.
let multipleDelegates = Delegate.Remove(multipleDelegates, vowelStart) :?> CheckAndDisplayDelegate
let multipleDelegates = Delegate.Combine(multipleDelegates, conStart) :?> CheckAndDisplayDelegate
// Pass multipleDelegates to DisplayAllQualified again.
printfn "\nExecuting the multipleDelegate delegate with two conStart delegates:"
printfn $"{multipleDelegates}"
0
// The example displays the following output:
// conStart contains 1 delegate(s).
// vowelStart contains 1 delegate(s).
//
// conStart and vowelStart are derived from MulticastDelegate.
//
// Executing the conStart delegate:
// This
// multicast
// delegate
//
// Executing the vowelStart delegate:
// is
// a
// example
//
//
// multipleDelegates contains 2 delegates.
//
// Executing the multipleDelegate delegate.
// This
// is
// a
// multicast
// delegate
// example
//
// Executing the multipleDelegate delegate with two conStart delegates:
// This
// This
// multicast
// multicast
// delegate
// delegate
Imports System.Collections.Generic
Class StringContainer
' Define a delegate to handle string display.
Delegate Sub CheckAndPrintDelegate(ByVal str As String)
' A generic list object that holds the strings.
Private container As New List(Of String)()
' A method that adds strings to the collection.
Public Sub AddString(ByVal s As String)
container.Add(s)
End Sub
' Iterate through the strings and invoke the method(s) that the delegate points to.
Public Sub DisplayAllQualified(ByVal displayDelegate As CheckAndPrintDelegate)
For Each s In container
displayDelegate(s)
Next
End Sub
End Class
' This class defines some methods to display strings.
Class StringExtensions
' Display a string if it starts with a consonant.
Public Shared Sub ConStart(ByVal str As String)
If Not (str.Chars(0) = "a"c Or str.Chars(0) = "e"c Or str.Chars(0) = "i"c _
Or str.Chars(0) = "o"c Or str.Chars(0) = "u"c) Then
Console.WriteLine(str)
End If
End Sub
' Display a string if it starts with a vowel.
Public Shared Sub VowelStart(ByVal str As String)
If (str.Chars(0) = "a"c Or str.Chars(0) = "e"c Or str.Chars(0) = "i"c _
Or str.Chars(0) = "o"c Or str.Chars(0) = "u"c) Then
Console.WriteLine(str)
End If
End Sub
End Class
' Demonstrate the use of delegates, including the Remove and
' Combine methods to create and modify delegate combinations.
Class Test
Public Shared Sub Main()
' Declare the StringContainer class and add some strings
Dim container As New StringContainer()
container.AddString("this")
container.AddString("is")
container.AddString("a")
container.AddString("multicast")
container.AddString("delegate")
container.AddString("example")
' Create two delegates individually using different methods.
Dim constart As StringContainer.CheckAndPrintDelegate = AddressOf StringExtensions.ConStart
Dim vowelStart As StringContainer.CheckAndPrintDelegate = AddressOf StringExtensions.VowelStart
' Get the list of all delegates assigned to this MulticastDelegate instance.
Dim delegateList() As [Delegate] = conStart.GetInvocationList()
Console.WriteLine("conStart contains {0} delegate(s).", delegateList.Length)
delegateList = vowelStart.GetInvocationList()
Console.WriteLine("vowelStart contains {0} delegate(s).", delegateList.Length)
Console.WriteLine()
' Determine whether the delegates are System.Multicast delegates
If TypeOf conStart Is System.MulticastDelegate And TypeOf vowelStart Is System.MulticastDelegate Then
Console.WriteLine("conStart and vowelStart are derived from MulticastDelegate.")
Console.WriteLine()
End If
' Run the two single delegates one after the other.
Console.WriteLine("Executing the conStart delegate:")
container.DisplayAllQualified(conStart)
Console.WriteLine("Executing the vowelStart delegate:")
container.DisplayAllQualified(vowelStart)
Console.WriteLine()
' Create a new MulticastDelegate and call Combine to add two delegates.
Dim multipleDelegates As StringContainer.CheckAndPrintDelegate =
CType([Delegate].Combine(conStart, vowelStart),
StringContainer.CheckAndPrintDelegate)
' How many delegates does multipleDelegates contain?
delegateList = multipleDelegates.GetInvocationList()
Console.WriteLine("{1}multipleDelegates contains {0} delegates.{1}",
delegateList.Length, vbCrLf)
' Pass this mulitcast delegate to DisplayAllQualified.
Console.WriteLine("Executing the multipleDelegate delegate.")
container.DisplayAllQualified(multipleDelegates)
' Call remove and combine to change the contained delegates.
multipleDelegates = CType([Delegate].Remove(multipleDelegates, vowelStart),
StringContainer.CheckAndPrintDelegate)
multipleDelegates = CType([Delegate].Combine(multipleDelegates, conStart),
StringContainer.CheckAndPrintDelegate)
' Pass multipleDelegates to DisplayAllQualified again.
Console.WriteLine()
Console.WriteLine("Executing the multipleDelegate delegate with two conStart delegates:")
container.DisplayAllQualified(multipleDelegates)
End Sub
End Class
' The example displays the following output:
' conStart contains 1 delegate(s).
' vowelStart contains 1 delegate(s).
'
' conStart and vowelStart are derived from MulticastDelegate.
'
' Executing the conStart delegate:
' This
' multicast
' delegate
'
' Executing the vowelStart delegate:
' is
' a
' example
'
'
' multipleDelegates contains 2 delegates.
'
' Executing the multipleDelegate delegate.
' This
' is
' a
' multicast
' delegate
' example
'
' Executing the multipleDelegate delegate with two conStart delegates:
' This
' This
' multicast
' multicast
' delegate
' delegate
Comentários
MulticastDelegate é uma classe especial. Compiladores e outras ferramentas podem derivar dessa classe, mas você não pode derivar dela explicitamente. O mesmo acontece com a classe Delegate.
Além dos métodos que os tipos delegados herdam de MulticastDelegate, o common language runtime fornece dois métodos especiais: BeginInvoke
e EndInvoke
. Para obter mais informações sobre esses métodos, consulte Chamando métodos síncronos de forma assíncrona.
Um MulticastDelegate tem uma lista vinculada de delegados, chamada de lista de invocação, que consiste em um ou mais elementos. Quando um delegado multicast é invocado, os delegados na lista de invocação são chamados de forma síncrona na ordem em que aparecem. Se ocorrer um erro durante a execução da lista, uma exceção será gerada.
Construtores
MulticastDelegate(Object, String) |
Inicializa uma nova instância da classe MulticastDelegate. |
MulticastDelegate(Type, String) |
Inicializa uma nova instância da classe MulticastDelegate. |
Propriedades
HasSingleTarget |
Obtém um valor que indica se o Delegate tem um único destino de invocação. (Herdado de Delegate) |
Method |
Obtém o método representado pelo delegado. (Herdado de Delegate) |
Target |
Obtém a instância de classe na qual o delegado atual invoca o método de instância. (Herdado de Delegate) |
Métodos
Clone() |
Cria uma cópia superficial do delegado. (Herdado de Delegate) |
CombineImpl(Delegate) |
Combina esse Delegate com o Delegate especificado para formar um novo delegado. |
CombineImpl(Delegate) |
Concatena as listas de invocação do delegado multicast especificado (combinável) e do delegado multicast atual (combinável). (Herdado de Delegate) |
DynamicInvoke(Object[]) |
Invoca dinamicamente (com limite tardio) o método representado pelo delegado atual. (Herdado de Delegate) |
DynamicInvokeImpl(Object[]) |
Processa a lista de invocação completa. |
DynamicInvokeImpl(Object[]) |
Invoca dinamicamente (com limite tardio) o método representado pelo delegado atual. (Herdado de Delegate) |
Equals(Object) |
Determina se esse delegado multicast e o objeto especificado são iguais. |
GetHashCode() |
Retorna o código hash dessa instância. |
GetInvocationList() |
Retorna a lista de invocação deste delegado multicast, em ordem de invocação. |
GetMethodImpl() |
Retorna um método representado pelo MulticastDelegateatual. |
GetMethodImpl() |
Obtém o método representado pelo delegado atual. (Herdado de Delegate) |
GetObjectData(SerializationInfo, StreamingContext) |
Obsoleto.
Popula um objeto SerializationInfo com todos os dados necessários para serializar essa instância. |
GetObjectData(SerializationInfo, StreamingContext) |
Obsoleto.
Não há suporte. (Herdado de Delegate) |
GetType() |
Obtém o Type da instância atual. (Herdado de Object) |
MemberwiseClone() |
Cria uma cópia superficial do Objectatual. (Herdado de Object) |
RemoveImpl(Delegate) |
Remove um elemento da lista de invocação deste MulticastDelegate que é igual ao delegado especificado. |
RemoveImpl(Delegate) |
Remove a lista de invocação de um delegado da lista de invocação de outro delegado. (Herdado de Delegate) |
ToString() |
Retorna uma cadeia de caracteres que representa o objeto atual. (Herdado de Object) |
Operadores
Equality(MulticastDelegate, MulticastDelegate) |
Determina se dois objetos MulticastDelegate são iguais. |
Inequality(MulticastDelegate, MulticastDelegate) |
Determina se dois objetos MulticastDelegate não são iguais. |
Métodos de Extensão
GetMethodInfo(Delegate) |
Obtém um objeto que representa o método representado pelo delegado especificado. |
Aplica-se a
Comentários
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