Este artículo se tradujo automáticamente. Para ver el artículo en inglés, active la casilla Inglés. Además, puede mostrar el texto en inglés en una ventana emergente si mueve el puntero del mouse sobre el texto.
Traducción
Inglés

Delegado Action<T1, T2, T3>

 

Publicado: octubre de 2016

Encapsula un método que tiene tres parámetros y no devuelve un valor.

Espacio de nombres:   System
Ensamblado:  mscorlib (en mscorlib.dll)

public delegate void Action<in T1, in T2, in T3>(
	T1 arg1,
	T2 arg2,
	T3 arg3
)

Parámetros

arg1
Type: T1

Primer parámetro del método que este delegado encapsula.

arg2
Type: T2

Segundo parámetro del método que este delegado encapsula.

arg3
Type: T3

Tercer parámetro del método que este delegado encapsula.

Parámetros de tipo

inT1

Tipo del primer parámetro del método que este delegado encapsula.

inT2

Tipo del segundo parámetro del método que este delegado encapsula.

inT3

Tipo del tercer parámetro del método que este delegado encapsula.

You can use the T:System.Action`3 delegate to pass a method as a parameter without explicitly declaring a custom delegate. The encapsulated method must correspond to the method signature that is defined by this delegate. This means that the encapsulated method must have three parameters that are all passed to it by value, and it must not return a value. (In C#, the method must return void. In Visual Basic, it must be defined by the Sub…End Sub construct. It can also be a method that returns a value that is ignored.) Typically, such a method is used to perform an operation.

System_CAPS_noteNota

To reference a method that has three parameters and returns a value, use the generic T:System.Func`4 delegate instead.

When you use the T:System.Action`3 delegate, you do not have to explicitly define a delegate that encapsulates a method with three parameters. For example, the following code explicitly declares a delegate named StringCopy and assigns a reference to the CopyStrings method to its delegate instance.

using System;

delegate void StringCopy(string[] stringArray1, 
                         string[] stringArray2, 
                         int indexToStart);

public class TestDelegate
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      StringCopy copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }

}

The following example simplifies this code by instantiating the T:System.Action`3 delegate instead of explicitly defining a new delegate and assigning a named method to it.

using System;

public class TestAction3
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}

You can also use the T:System.Action`3 delegate with anonymous methods in C#, as the following example illustrates. (For an introduction to anonymous methods, see Anonymous Methods (C# Programming Guide).)

using System;

public class TestAnon
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = delegate(string[] s1, 
                                                               string[] s2, 
                                                               int pos) 
                                      { CopyStrings(s1, s2, pos); };
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}

You can also assign a lambda expression to an T:System.Action`3 delegate instance, as the following example illustrates. (For an introduction to lambda expressions, see Lambda Expressions (C# Programming Guide).)

using System;

public class TestLambda
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int> copyOperation = (s1, s2, pos) =>
                                      CopyStrings(s1, s2, pos); 
      copyOperation(ordinals, copiedOrdinals, 3);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(ordinal == string.Empty ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, int startPos)
   {
      if (source.Length != target.Length) 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.");

      for (int ctr = startPos; ctr <= source.Length - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}

Plataforma universal de Windows
Disponible desde 8
.NET Framework
Disponible desde 3.5
Biblioteca de clases portable
Se admite en: plataformas portátiles de .NET
Silverlight
Disponible desde 2.0
Windows Phone Silverlight
Disponible desde 7.0
Windows Phone
Disponible desde 8.1
Volver al principio
Mostrar: