Signals in Visual Basic .NET

Here’s an idiomatic Visual Basic .NET example demonstrating signal handling, similar to the concept shown in the Go example:

Imports System
Imports System.Threading

Module SignalHandling
    Private ReadOnly signalReceived As New ManualResetEvent(False)

    Sub Main()
        ' Set up console control handler
        AddHandler Console.CancelKeyPress, AddressOf Console_CancelKeyPress

        Console.WriteLine("Awaiting signal...")

        ' Wait for the signal
        signalReceived.WaitOne()

        Console.WriteLine("Exiting")
    End Sub

    Private Sub Console_CancelKeyPress(sender As Object, e As ConsoleCancelEventArgs)
        Console.WriteLine()
        Console.WriteLine($"Received signal: {e.SpecialKey}")

        ' Prevent the process from terminating immediately
        e.Cancel = True

        ' Signal that we've received the event
        signalReceived.Set()
    End Sub
End Module

This Visual Basic .NET example demonstrates how to handle console signals, which is similar to the concept of Unix signals in the Go example. Here’s an explanation of the code:

1. We import the necessary namespaces: System for basic functionality and System.Threading for the ManualResetEvent.

2. We define a ManualResetEvent called signalReceived to synchronize between the main thread and the signal handling event.

3. In the Main subroutine:

   • We set up a console control handler by adding an event handler for the Console.CancelKeyPress event.
   • We print a message indicating that we’re waiting for a signal.
   • We use signalReceived.WaitOne() to block the main thread until a signal is received.

4. The Console_CancelKeyPress subroutine is our event handler for console signals:

   • It prints the type of signal received (e.g., ControlC for Ctrl+C).
   • We set e.Cancel = True to prevent the process from terminating immediately.
   • We call signalReceived.Set() to unblock the main thread.

To run this program:

1. Save the code in a file named SignalHandling.vb.
2. Open a command prompt and navigate to the directory containing the file.
3. Compile the code using the Visual Basic compiler:

vbc SignalHandling.vb

4. Run the compiled executable:

SignalHandling.exe

The program will wait for you to press Ctrl+C (or Ctrl+Break). When you do, it will print the signal received and then exit.

This example demonstrates how to handle console signals in Visual Basic .NET, which is conceptually similar to handling Unix signals in Go. While VB.NET doesn’t have direct equivalents to Unix signals, the Console.CancelKeyPress event provides a way to intercept and handle termination requests in console applications.