Action<T1,T2,T3,T4> Action<T1,T2,T3,T4> Action<T1,T2,T3,T4> Action<T1,T2,T3,T4> Delegate

Definice

Zapouzdřuje metodu, která má čtyři parametry a nevrací hodnotu.Encapsulates a method that has four parameters and does not return a value.

generic <typename T1, typename T2, typename T3, typename T4>
public delegate void Action(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
public delegate void Action<in T1,in T2,in T3,in T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
type Action<'T1, 'T2, 'T3, 'T4> = delegate of 'T1 * 'T2 * 'T3 * 'T4 -> unit
Public Delegate Sub Action(Of In T1, In T2, In T3, In T4)(arg1 As T1, arg2 As T2, arg3 As T3, arg4 As T4)

Parametry typu

T1

Typ prvního parametru metody, kterou tento delegát zapouzdřuje.The type of the first parameter of the method that this delegate encapsulates.

T2

Typ druhého parametru metody, kterou tento delegát zapouzdřuje.The type of the second parameter of the method that this delegate encapsulates.

T3

Typ třetího parametru metody, kterou tento delegát zapouzdřuje.The type of the third parameter of the method that this delegate encapsulates.

T4

Typ čtvrtého parametru metody, kterou tento delegát zapouzdřuje.The type of the fourth parameter of the method that this delegate encapsulates.

Parametry

arg1

První parametr metody, kterou tento delegát zapouzdřuje.The first parameter of the method that this delegate encapsulates.

arg2

Druhý parametr metody, kterou tento delegát zapouzdřuje.The second parameter of the method that this delegate encapsulates.

arg3

Třetí parametr metody, kterou tento delegát zapouzdřuje.The third parameter of the method that this delegate encapsulates.

arg4

Čtvrtý parametr metody, který tento delegát zapouzdřuje.The fourth parameter of the method that this delegate encapsulates.

Dědičnost
Action<T1,T2,T3,T4>Action<T1,T2,T3,T4>Action<T1,T2,T3,T4>Action<T1,T2,T3,T4>

Poznámky

Action<T1,T2,T3,T4> Delegáta můžete použít k předání metody jako parametru bez explicitního deklarování vlastního delegáta.You can use the Action<T1,T2,T3,T4> delegate to pass a method as a parameter without explicitly declaring a custom delegate. Zapouzdřená metoda musí odpovídat podpisu metody, která je definována tímto delegátem.The encapsulated method must correspond to the method signature that is defined by this delegate. To znamená, že zapouzdřená metoda musí mít čtyři parametry, které jsou předány na základě hodnoty a nesmí vracet hodnotu.This means that the encapsulated method must have four parameters that are all passed to it by value, and it must not return a value. (V C#nástroji musí metoda vracet void.(In C#, the method must return void. V Visual Basic musí být definován pomocí Sub...End SubIn Visual Basic, it must be defined by the SubEnd Sub Contains.construct. Může to být také metoda, která vrací hodnotu, která je ignorována.) Obvykle se tato metoda používá k provedení operace.It can also be a method that returns a value that is ignored.) Typically, such a method is used to perform an operation.

Poznámka

Chcete-li odkazovat na metodu, která má čtyři parametry a vrací hodnotu, použijte Func<T1,T2,T3,T4,TResult> místo toho obecného delegáta.To reference a method that has four parameters and returns a value, use the generic Func<T1,T2,T3,T4,TResult> delegate instead.

Když použijete Action<T1,T2,T3,T4> delegáta, nemusíte explicitně definovat delegáta, který zapouzdřuje metodu se čtyřmi parametry.When you use the Action<T1,T2,T3,T4> delegate, you do not have to explicitly define a delegate that encapsulates a method with four parameters. Například následující kód explicitně deklaruje delegáta s názvem StringCopy a přiřadí odkaz CopyStrings na metodu jeho instanci delegáta.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,
                         int numberToCopy);
                         
public class TestDelegate
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth", 
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      StringCopy copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3, 5);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, 
                                   int startPos, int number)
   {
      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 <= startPos + number - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}
Delegate Sub StringCopy(stringArray1() As String, _
                        stringArray2() As String, _
                        indexToStart As Integer, _
                        numberToCopy As Integer)

Module TestDelegate
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", _
                                  "Fifth", "Sixth", "Seventh", "Eighth", _
                                  "Ninth", "Tenth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String
      Dim copyOperation As StringCopy = AddressOf CopyStrings
      copyOperation(ordinals, copiedOrdinals, 3, 5)
      For Each ordinal As String In copiedOrdinals
         Console.WriteLine(ordinal)
      Next    
   End Sub
   
   Private Sub CopyStrings(source() As String, target() As String, _
                           startPos As Integer, number As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays" & _
                   " must have the same number of elements.")
      End If
      For ctr As Integer = startPos to startpos + number  - 1
         target(ctr) = String.Copy(source(ctr))
      Next
   End Sub
End Module

Následující příklad zjednodušuje tento kód vytvořením instance Action<T1,T2,T3,T4> delegáta místo explicitního definování nového delegáta a přiřazením pojmenované metody k němu.The following example simplifies this code by instantiating the Action<T1,T2,T3,T4> delegate instead of explicitly defining a new delegate and assigning a named method to it.

using System;

public class TestAction4
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth", 
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int, int> copyOperation = CopyStrings;
      copyOperation(ordinals, copiedOrdinals, 3, 5);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, 
                                   int startPos, int number)
   {
      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 <= startPos + number - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}
Module TestAction4
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", _
                                  "Fifth", "Sixth", "Seventh", "Eighth", _
                                  "Ninth", "Tenth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String
      Dim copyOperation As Action(Of String(), String(), Integer, Integer) = _
                           AddressOf CopyStrings
      copyOperation(ordinals, copiedOrdinals, 3, 5)
      For Each ordinal As String In copiedOrdinals
         Console.WriteLine(ordinal)
      Next    
   End Sub
   
   Private Sub CopyStrings(source() As String, target() As String, _
                           startPos As Integer, number As Integer)
      If source.Length <> target.Length Then 
         Throw New IndexOutOfRangeException("The source and target arrays" & _
                   " must have the same number of elements.")
      End If
      For ctr As Integer = startPos to startpos + number  - 1
         target(ctr) = String.Copy(source(ctr))
      Next
   End Sub
End Module

Můžete také použít Action<T1,T2,T3,T4> delegáta s anonymními metodami C#v, jak ukazuje následující příklad.You can also use the Action<T1,T2,T3,T4> delegate with anonymous methods in C#, as the following example illustrates. (Úvod do anonymních metod naleznete v tématu Anonymous Methods.)(For an introduction to anonymous methods, see Anonymous Methods.)

using System;

public class TestAnonymousMethod
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth", 
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int, int> copyOperation = 
                                           delegate(string[] s1, string[] s2, 
                                           int pos, int num) 
                                { CopyStrings(s1, s2, pos, num); };  
      copyOperation(ordinals, copiedOrdinals, 3, 5);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, 
                                   int startPos, int number)
   {
      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 <= startPos + number - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}

Lambda výraz Action<T1,T2,T3,T4> můžete také přiřadit instanci delegáta, jak ukazuje následující příklad.You can also assign a lambda expression to an Action<T1,T2,T3,T4> delegate instance, as the following example illustrates. (Úvod do výrazů lambda naleznete v tématu lambda Expressions.)(For an introduction to lambda expressions, see Lambda Expressions.)

using System;

public class TestLambdaExpression
{
   public static void Main()
   {
      string[] ordinals = {"First", "Second", "Third", "Fourth", "Fifth", 
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"};
      string[] copiedOrdinals = new string[ordinals.Length];           
      Action<string[], string[], int, int> copyOperation = (s1, s2, pos, num)
                                           => CopyStrings(s1, s2, pos, num);  
      copyOperation(ordinals, copiedOrdinals, 3, 5);
      foreach (string ordinal in copiedOrdinals)
         Console.WriteLine(String.IsNullOrEmpty(ordinal) ? "<None>" : ordinal);
   }

   private static void CopyStrings(string[] source, string[] target, 
                                   int startPos, int number)
   {
      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 <= startPos + number - 1; ctr++)
         target[ctr] = String.Copy(source[ctr]);
   }
}
Public Module TestLambdaExpression
   Public Sub Main()
      Dim ordinals() As String = {"First", "Second", "Third", "Fourth", "Fifth", _ 
                           "Sixth", "Seventh", "Eighth", "Ninth", "Tenth"}
      Dim copiedOrdinals(ordinals.Length - 1) As String           
      Dim copyOperation As Action(Of String(), String(), Integer, Integer) = _
                           Sub(s1, s2, pos, num) CopyStrings(s1, s2, pos, num)  
      copyOperation(ordinals, copiedOrdinals, 3, 5)
      For Each ordinal As String In copiedOrdinals
         If String.IsNullOrEmpty(ordinal) Then
            Console.WriteLine("<None>")
         Else
            Console.WriteLine(ordinal)
         End If
      Next   
   End Sub

   Private Function CopyStrings(source() As String, target() As String, _ 
                                startPos As Integer, number As Integer) As Integer
      If source.Length <> target.Length Then 
         throw new IndexOutOfRangeException("The source and target arrays must have the same number of elements.")
      End If
      
      For ctr As Integer = startPos To startPos + number - 1
         target(ctr) = String.Copy(source(ctr))
      Next
      Return number
   End Function
End Module
' The example displays the following output:
'       Fourth
'       Fifth
'       Sixth
'       Seventh
'       Eighth

Metody rozšíření

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

Získává objekt, který představuje metodu reprezentovanou zadaným delegátem.Gets an object that represents the method represented by the specified delegate.

Platí pro

Viz také