MulticastDelegate MulticastDelegate MulticastDelegate MulticastDelegate Class

Definizione

Rappresenta un delegato multicast, ossia un delegato che può avere più di un elemento nell'elenco chiamate.Represents a multicast delegate; that is, a delegate that can have more than one element in its invocation list.

public ref class MulticastDelegate abstract : Delegate
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public abstract class MulticastDelegate : Delegate
type MulticastDelegate = class
    inherit Delegate
Public MustInherit Class MulticastDelegate
Inherits Delegate
Ereditarietà
MulticastDelegateMulticastDelegateMulticastDelegateMulticastDelegate
Attributi

Esempi

Nell'esempio seguente viene definita una classe StringContainer,, che include una raccolta di stringhe.The following example defines a class, StringContainer, which includes a collection of strings. Uno dei suoi membri è il CheckAndDisplayDelegate delegato, che viene usato per visualizzare le stringhe archiviate StringContainer in un oggetto che soddisfano determinati criteri.One of its members is the CheckAndDisplayDelegate delegate, which is used to display strings stored in a StringContainer object that satisfy particular criteria. Il delegato accetta una singola stringa come parametro e restituisce void (o, in Visual Basic, è una Sub procedura).The delegate takes a single string as a parameter and returns void (or, in Visual Basic, it's a Sub procedure). Include anche un metodo, DisplayAllQualified, che dispone di un singolo parametro, un CheckAndDisplayDelegate delegato.It also includes a method, DisplayAllQualified, that has a single parameter, a CheckAndDisplayDelegate delegate. In questo modo è possibile chiamare il metodo e visualizzare un set di stringhe filtrate in base ai metodi contenuti nel delegato.This allows the method to be called and to display a set of strings that are filtered based on the methods that the delegate contains.

Nell'esempio viene inoltre definita una classe di StringExtensionsutilità,, che dispone di due metodi:The example also defines a utility class, StringExtensions, that has two methods:

  • ConStart, che visualizza le stringhe che iniziano con una consonante.ConStart, which displays strings that begin with a consonant.

  • VowelStart, che visualizza le stringhe che iniziano con una vocale.VowelStart, which displays strings that begin with a vowel.

Si noti che entrambi i metodi includono un solo parametro di voidstringa e restituiscono.Note that both methods include a single string parameter and return void. In altre parole, entrambi i CheckAndDisplayDelegate metodi possono essere assegnati al delegato.In other words, both methods can be assigned to the CheckAndDisplayDelegate delegate.

Il Test.Main metodo è il punto di ingresso dell'applicazione.The Test.Main method is the application entry point. Crea un'istanza di StringContainer un oggetto, lo popola con stringhe e crea due CheckAndDisplayDelegate delegati conStart , vowelStarte, che richiamano un singolo metodo.It instantiates a StringContainer object, populates it with strings, and creates two CheckAndDisplayDelegate delegates, conStart and vowelStart, that invoke a single method. Viene quindi chiamato il Delegate.Combine metodo per creare il multipleDelegates delegato, che inizialmente contiene i ConStart delegati e VowelStart .It then calls the Delegate.Combine method to create the multipleDelegates delegate, which initially contains the ConStart and VowelStart delegates. Si noti che quando multipleDelegates viene richiamato il delegato, vengono visualizzate tutte le stringhe della raccolta nell'ordine originale.Note that when the multipleDelegates delegate is invoked, it displays all the strings in the collection in their original order. Questo perché ogni lettera viene passata separatamente a ogni delegato e ogni lettera soddisfa i criteri di filtro di uno solo dei due delegati.This is because each letter is passed separately to each delegate, and each letter meets the filtering criteria of only one of the two delegates. Infine, dopo le chiamate Delegate.Remove a Delegate.Combinee multipleDelegates , contiene conStart due delegati.Finally, after calls to Delegate.Remove and Delegate.Combine, multipleDelegates contains two conStart delegates. Quando viene richiamato, ogni stringa nell' StringContainer oggetto viene visualizzata due volte.When it is invoked, each string in the StringContainer object is displayed twice.

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
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

Commenti

MulticastDelegateè una classe speciale.MulticastDelegate is a special class. I compilatori e altri strumenti possono derivare da questa classe, ma non è possibile derivare da essa in modo esplicito.Compilers and other tools can derive from this class, but you cannot derive from it explicitly. Lo stesso vale per la Delegate classe.The same is true of the Delegate class.

Oltre ai metodi dai quali i tipi delegati MulticastDelegateereditano da, il Common Language Runtime fornisce due BeginInvoke metodi EndInvokespeciali: e.In addition to the methods that delegate types inherit from MulticastDelegate, the common language runtime provides two special methods: BeginInvoke and EndInvoke. Per ulteriori informazioni su questi metodi, vedere chiamata asincrona dei metodi sincroni.For more information about these methods, see Calling Synchronous Methods Asynchronously.

Un MulticastDelegate oggetto ha un elenco collegato di delegati, denominato elenco chiamate, costituito da uno o più elementi.A MulticastDelegate has a linked list of delegates, called an invocation list, consisting of one or more elements. Quando viene richiamato un delegato multicast, i delegati nell'elenco chiamate vengono chiamati in modo sincrono nell'ordine in cui vengono visualizzati.When a multicast delegate is invoked, the delegates in the invocation list are called synchronously in the order in which they appear. Se si verifica un errore durante l'esecuzione dell'elenco, viene generata un'eccezione.If an error occurs during execution of the list then an exception is thrown.

Costruttori

MulticastDelegate(Object, String) MulticastDelegate(Object, String) MulticastDelegate(Object, String) MulticastDelegate(Object, String)

Inizializza una nuova istanza della classe MulticastDelegate.Initializes a new instance of the MulticastDelegate class.

MulticastDelegate(Type, String) MulticastDelegate(Type, String) MulticastDelegate(Type, String) MulticastDelegate(Type, String)

Inizializza una nuova istanza della classe MulticastDelegate.Initializes a new instance of the MulticastDelegate class.

Metodi

Clone() Clone() Clone() Clone()

Crea una copia superficiale del delegato.Creates a shallow copy of the delegate.

(Inherited from Delegate)
CombineImpl(Delegate) CombineImpl(Delegate) CombineImpl(Delegate) CombineImpl(Delegate)

Associa l'oggetto Delegate con l'oggetto Delegate specificato per creare un nuovo delegato.Combines this Delegate with the specified Delegate to form a new delegate.

DynamicInvoke(Object[]) DynamicInvoke(Object[]) DynamicInvoke(Object[]) DynamicInvoke(Object[])

Richiama dinamicamente, ovvero ad associazione tardiva, il metodo rappresentato dal delegato corrente.Dynamically invokes (late-bound) the method represented by the current delegate.

(Inherited from Delegate)
DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[]) DynamicInvokeImpl(Object[])

Elabora l'elenco completo delle chiamate.Processes the full invocation list.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina se questo delegato multicast e l'oggetto specificato sono uguali.Determines whether this multicast delegate and the specified object are equal.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Restituisce il codice hash per l'istanza.Returns the hash code for this instance.

GetInvocationList() GetInvocationList() GetInvocationList() GetInvocationList()

Restituisce l'elenco chiamate di questo delegato multicast, in ordine di chiamata.Returns the invocation list of this multicast delegate, in invocation order.

GetMethodImpl() GetMethodImpl() GetMethodImpl() GetMethodImpl()

Restituisce un metodo statico rappresentato dall'oggetto MulticastDelegate corrente.Returns a static method represented by the current MulticastDelegate.

GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext) GetObjectData(SerializationInfo, StreamingContext)

Compila un oggetto SerializationInfo con tutti i dati necessari per serializzare questa istanza.Populates a SerializationInfo object with all the data needed to serialize this instance.

GetType() GetType() GetType() GetType()

Ottiene l'oggetto Type dell'istanza corrente.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crea una copia superficiale dell'oggetto Object corrente.Creates a shallow copy of the current Object.

(Inherited from Object)
RemoveImpl(Delegate) RemoveImpl(Delegate) RemoveImpl(Delegate) RemoveImpl(Delegate)

Rimuove un elemento uguale al delegato specificato dall'elenco chiamate di questo MulticastDelegate.Removes an element from the invocation list of this MulticastDelegate that is equal to the specified delegate.

ToString() ToString() ToString() ToString()

Restituisce una stringa che rappresenta l'oggetto corrente.Returns a string that represents the current object.

(Inherited from Object)

Operatori

Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate) Equality(MulticastDelegate, MulticastDelegate)

Determina se due oggetti MulticastDelegate sono uguali.Determines whether two MulticastDelegate objects are equal.

Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate) Inequality(MulticastDelegate, MulticastDelegate)

Determina se due oggetti MulticastDelegate non sono uguali.Determines whether two MulticastDelegate objects are not equal.

Proprietà

Method Method Method Method

Ottiene il metodo rappresentato dal delegato.Gets the method represented by the delegate.

(Inherited from Delegate)
Target Target Target Target

Ottiene l'istanza di classe sulla quale il metodo di istanza viene richiamato dal delegato corrente.Gets the class instance on which the current delegate invokes the instance method.

(Inherited from Delegate)

Metodi di estensione

GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate) GetMethodInfo(Delegate)

Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato.Gets an object that represents the method represented by the specified delegate.

Si applica a