Action Delegat

Definicja

Hermetyzuje metodę, która nie ma parametrów i nie zwraca wartości.Encapsulates a method that has no parameters and does not return a value.

public delegate void Action();
public delegate void Action();
type Action = delegate of unit -> unit
Public Delegate Sub Action()
Dziedziczenie
Action

Uwagi

Tego delegata można użyć do przekazania metody jako parametru bez jawnego deklarowania niestandardowego delegata.You can use this delegate to pass a method as a parameter without explicitly declaring a custom delegate. Metoda hermetyzowana musi odpowiadać sygnaturze metody zdefiniowanej przez tego delegata.The encapsulated method must correspond to the method signature that is defined by this delegate. Oznacza to, że metoda hermetyzowana nie może mieć parametrów i nie zwraca wartości.This means that the encapsulated method must have no parameters and no return value. (W C#, metoda musi zwracać void.(In C#, the method must return void. W Visual Basic musi on być zdefiniowany przez Sub...End SubIn Visual Basic, it must be defined by the SubEnd Sub Konstruuj.construct. Może być również metodą zwracającą wartość, która jest ignorowana.) Zazwyczaj taka metoda jest używana do wykonywania operacji.It can also be a method that returns a value that is ignored.) Typically, such a method is used to perform an operation.

Uwaga

Aby odwołać się do metody, która nie ma parametrów i zwraca wartość, należy zamiast tego użyć delegata generycznego Func<TResult>.To reference a method that has no parameters and returns a value, use the generic Func<TResult> delegate instead.

W przypadku korzystania z delegata Action nie trzeba jawnie definiować delegata, który hermetyzuje procedurę bez parametrów.When you use the Action delegate, you do not have to explicitly define a delegate that encapsulates a parameterless procedure. Na przykład poniższy kod jawnie deklaruje delegata o nazwie ShowValue i przypisuje odwołanie do metody wystąpienia Name.DisplayToWindow do jego wystąpienia delegata.For example, the following code explicitly declares a delegate named ShowValue and assigns a reference to the Name.DisplayToWindow instance method to its delegate instance.

using namespace System;
using namespace System::Windows::Forms;

public delegate void ShowValue();


public ref class Name
{
private:
   String^ instanceName;

public:
   Name(String^ name) 
   {
      instanceName = name;
   }

   void DisplayToConsole()
   {
      Console::WriteLine(this->instanceName);
   }

   void DisplayToWindow()
   {
      MessageBox::Show(this->instanceName);
   }
};

int main()
{
   Name^ testName = gcnew Name(L"Koani");
   ShowValue^ showMethod;
   showMethod = gcnew ShowValue(testName, &Name::DisplayToWindow);
   showMethod();
   return 0;
}
using System;
using System.Windows.Forms;

public delegate void ShowValue();

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class testTestDelegate
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      ShowValue showMethod = testName.DisplayToWindow;
      showMethod();
   }
}
Public Delegate Sub ShowValue

Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Sub DisplayToConsole()
      Console.WriteLine(Me.instanceName)
   End Sub   
   
   Public Sub DisplayToWindow()
      MsgBox(Me.instanceName)
   End Sub   
End Class

Public Module testDelegate
   Public Sub Main()
      Dim testName As New Name("Koani")
      Dim showMethod As ShowValue = AddressOf testName.DisplayToWindow
      showMethod   
   End Sub
End Module

Poniższy przykład upraszcza ten kod, tworząc wystąpienie delegata Action, zamiast jawnie definiując nowy delegat i przypisując nazwaną metodę.The following example simplifies this code by instantiating the Action delegate instead of explicitly defining a new delegate and assigning a named method to it.

#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::Windows::Forms;

public ref class Name
{
private:
   String^ instanceName;
   
public:
   Name(String^ name)
   {
      instanceName = name;
   }

   void DisplayToConsole()
   {
      Console::WriteLine(this->instanceName);
   }

   void DisplayToWindow()
   {
      MessageBox::Show(this->instanceName);
   }
};


int main()
{
   Name^ testName = gcnew Name(L"Koani");
   System::Action^ showMethod;
   showMethod += gcnew Action(testName, &Name::DisplayToWindow);
   showMethod();
   return 0;
}
using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class testTestDelegate
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = testName.DisplayToWindow;
      showMethod();
   }
}
Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Sub DisplayToConsole()
      Console.WriteLine(Me.instanceName)
   End Sub   
   
   Public Sub DisplayToWindow()
      MsgBox(Me.instanceName)
   End Sub   
End Class

Public Module testDelegate
   Public Sub Main()
      Dim testName As New Name("Koani")
      Dim showMethod As Action = AddressOf testName.DisplayToWindow
      showMethod   
   End Sub
End Module

Można również użyć delegata Action z metodami anonimowymi C#w, jak pokazano w poniższym przykładzie.You can also use the Action delegate with anonymous methods in C#, as the following example illustrates. (Aby uzyskać wprowadzenie do metod anonimowych, zobacz metody anonimowe).(For an introduction to anonymous methods, see Anonymous Methods.)

using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class Anonymous
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = delegate() { testName.DisplayToWindow();} ;
      showMethod();
   }
}

Można również przypisać wyrażenie lambda do wystąpienia Action delegata, jak pokazano w poniższym przykładzie.You can also assign a lambda expression to an Action delegate instance, as the following example illustrates. (Aby uzyskać wprowadzenie do wyrażeń lambda, zobacz lambda Expressions).(For an introduction to lambda expressions, see Lambda Expressions.)

using System;
using System.Windows.Forms;

public class Name
{
   private string instanceName;
   
   public Name(string name)
   {
      this.instanceName = name;
   }

   public void DisplayToConsole()
   {
      Console.WriteLine(this.instanceName);
   }

   public void DisplayToWindow()
   {
      MessageBox.Show(this.instanceName);
   }
}

public class LambdaExpression
{
   public static void Main()
   {
      Name testName = new Name("Koani");
      Action showMethod = () => testName.DisplayToWindow();
      showMethod();
   }
}
Public Class Name
   Private instanceName As String
   
   Public Sub New(name As String)
      Me.instanceName = name
   End Sub
   
   Public Function DisplayToConsole() As Integer
      Console.WriteLine(Me.instanceName)
      Return 0
   End Function
   
   Public Function DisplayToWindow() As Integer
      Return MsgBox(Me.instanceName)
   End Function      
End Class

Module LambdaExpression
   Public Sub Main()
      Dim name1 As New Name("Koani")
      Dim methodCall As Action = Sub() name1.DisplayToWindow()
      methodCall()
   End Sub
End Module

Metody rozszerzania

GetMethodInfo(Delegate)

Pobiera obiekt, który reprezentuje metodę reprezentowaną przez określony delegat.Gets an object that represents the method represented by the specified delegate.

Dotyczy

Zobacz też