C# 委托（开发者如何使用）

// Delegate declaration
public delegate void MyDelegate(string message);
// Instantiation
MyDelegate myDelegate = DisplayMessage;
// Method to be referenced
static void DisplayMessage(string message)
{
    Console.WriteLine(message);
}
// Invocation
myDelegate("Hello, Delegates!");

' Delegate declaration
Public Delegate Sub MyDelegate(ByVal message As String)
' Instantiation
Private myDelegate As MyDelegate = AddressOf DisplayMessage
' Method to be referenced
Shared Sub DisplayMessage(ByVal message As String)
	Console.WriteLine(message)
End Sub
' Invocation
myDelegate("Hello, Delegates!")

class Program
{
static void Main(string [] args)
{
   public class EventPublisher
   {
       // Declare a delegate
       public delegate void EventHandler(string eventName);
       // Create an instance of the delegate
       public EventHandler EventOccurred;
       // Simulate an event
       public void SimulateEvent(string eventName)
       {
           // Invoke the delegate to notify subscribers
           EventOccurred?.Invoke(eventName);
       }
   }
   public class EventSubscriber
   {
       public EventSubscriber(EventPublisher eventPublisher)
       {
           // Subscribe to the event using the delegate
           eventPublisher.EventOccurred += HandleEvent;
       }
       // Method to be invoked when the event occurs
       private void HandleEvent(string eventName)
       {
           Console.WriteLine($"Event handled: {eventName}");
       }
   }
}
}

Friend Class Program
Shared Sub Main(ByVal args() As String)
'INSTANT VB TODO TASK: Local functions are not converted by Instant VB:
'   public class EventPublisher
'   {
'	   ' Declare a delegate
'	   public delegate void EventHandler(string eventName);
'	   ' Create an instance of the delegate
'	   public EventHandler EventOccurred;
'	   ' Simulate an event
'	   public void SimulateEvent(string eventName)
'	   {
'		   ' Invoke the delegate to notify subscribers
'		   if (EventOccurred != Nothing)
'			   EventOccurred.Invoke(eventName);
'	   }
'   }
'INSTANT VB TODO TASK: Local functions are not converted by Instant VB:
'   public class EventSubscriber
'   {
'	   public EventSubscriber(EventPublisher eventPublisher)
'	   {
'		   ' Subscribe to the event using the delegate
'		   eventPublisher.EventOccurred += HandleEvent;
'	   }
'	   ' Method to be invoked when the event occurs
'	   private void HandleEvent(string eventName)
'	   {
'		   Console.WriteLine(string.Format("Event handled: {0}", eventName));
'	   }
'   }
End Sub
End Class

public delegate int MyDelegate(int x, int y);
public class Calculator
{
    public int PerformOperation(MyDelegate operation, int operand1, int operand2)
    {
        return operation(operand1, operand2);
    }
}
// Usage
var calculator = new Calculator();
int result = calculator.PerformOperation((x, y) => x + y, 5, 3); // Adds 5 and 3

Public Delegate Function MyDelegate(ByVal x As Integer, ByVal y As Integer) As Integer
Public Class Calculator
	Public Function PerformOperation(ByVal operation As MyDelegate, ByVal operand1 As Integer, ByVal operand2 As Integer) As Integer
		Return operation(operand1, operand2)
	End Function
End Class
' Usage
Private calculator = New Calculator()
Private result As Integer = calculator.PerformOperation(Function(x, y) x + y, 5, 3) ' Adds 5 and 3

string AddPassword(PdfDocument document)
{
    string password = "";
    if (document.Password == "")
    {
        password = "Iron123";   
    }
    return password;
}
PdfDocument document = new PdfDocument("StyledDocument.pdf");
AddPasswordEventHandler handler = AddPassword;
document.Password = handler.Invoke(document);  // Subscribe to the event
document.SaveAs("PasswordProtected.pdf");
public delegate string AddPasswordEventHandler(PdfDocument e);

Private Function AddPassword(ByVal document As PdfDocument) As String
	Dim password As String = ""
	If document.Password = "" Then
		password = "Iron123"
	End If
	Return password
End Function
Private document As New PdfDocument("StyledDocument.pdf")
Private handler As AddPasswordEventHandler = AddressOf AddPassword
document.Password = handler.Invoke(document) ' Subscribe to the event
document.SaveAs("PasswordProtected.pdf")
public delegate String AddPasswordEventHandler(PdfDocument e)

// Assuming GetDynamicContent is a delegate that generates dynamic HTML content
Func<string> getDynamicContent = () =>
{
    // Custom logic to generate dynamic content
    return "<p>This is dynamic content based on some condition.</p>";
};
// Incorporate dynamic HTML into the PDF
var pdfDocument = new ChromePdfRenderer();
pdfDocument.RenderHtmlAsPdf($"<html><body>{getDynamicContent()}</body></html>").SaveAs("DynamicContentDocument.pdf");

' Assuming GetDynamicContent is a delegate that generates dynamic HTML content
Dim getDynamicContent As Func(Of String) = Function()
	' Custom logic to generate dynamic content
	Return "<p>This is dynamic content based on some condition.</p>"
End Function
' Incorporate dynamic HTML into the PDF
Dim pdfDocument = New ChromePdfRenderer()
pdfDocument.RenderHtmlAsPdf($"<html><body>{getDynamicContent()}</body></html>").SaveAs("DynamicContentDocument.pdf")