Logging in Visual Basic .NET

Here’s an idiomatic Visual Basic .NET example demonstrating logging concepts:

Imports System
Imports System.IO
Imports System.Text

Module LoggingExample
    Sub Main()
        ' Simple console logging
        Console.WriteLine("Standard console output")

        ' Using the built-in Trace class for logging
        Trace.WriteLine("Trace output")

        ' Configure trace to include timestamp
        Trace.Listeners.Add(New TextWriterTraceListener(Console.Out))
        Trace.AutoFlush = True
        Trace.WriteLine("Trace with timestamp")

        ' Create a custom TraceListener
        Dim customListener As New CustomTraceListener()
        Trace.Listeners.Add(customListener)
        Trace.WriteLine("Custom formatted trace")

        ' Logging to a file
        Dim fileListener As New TextWriterTraceListener("application.log")
        Trace.Listeners.Add(fileListener)
        Trace.WriteLine("This will be written to the log file")

        ' Clean up
        Trace.Flush()
        fileListener.Close()

        ' Structured logging using a custom class
        Dim structuredLogger As New StructuredLogger()
        structuredLogger.LogInfo("User logged in", "userId", "12345", "loginTime", DateTime.Now)
    End Sub
End Module

' Custom TraceListener for formatted output
Class CustomTraceListener
    Inherits TraceListener

    Public Overrides Sub Write(message As String)
        Console.Write($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] {message}")
    End Sub

    Public Overrides Sub WriteLine(message As String)
        Console.WriteLine($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] {message}")
    End Sub
End Class

' Simple structured logger
Class StructuredLogger
    Public Sub LogInfo(message As String, ParamArray args As Object())
        Dim logBuilder As New StringBuilder()
        logBuilder.Append($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] INFO: {message}")

        For i As Integer = 0 To args.Length - 1 Step 2
            If i + 1 < args.Length Then
                logBuilder.Append($" {args(i)}={args(i + 1)}")
            End If
        Next

        Console.WriteLine(logBuilder.ToString())
    End Sub
End Class

This Visual Basic .NET example demonstrates various logging techniques:

We start with simple console output using Console.WriteLine().
We then use the built-in Trace class, which is part of the .NET Framework’s diagnostics tools.
We configure Trace to include timestamps by adding a TextWriterTraceListener.
A custom TraceListener is created to demonstrate how to format log messages.
File logging is demonstrated by adding a TextWriterTraceListener that writes to a file.
Finally, we implement a simple structured logger that allows adding key-value pairs to log messages.

To run this program:

Save the code in a file with a .vb extension (e.g., LoggingExample.vb).
Compile the code using the VB.NET compiler:

vbc LoggingExample.vb

Run the compiled executable:

LoggingExample.exe

This example shows how to use both built-in and custom logging mechanisms in Visual Basic .NET. It demonstrates console output, file logging, and a basic implementation of structured logging. The Trace class is used as an alternative to the log package in Go, providing similar functionality for debug and trace output.

Remember to add appropriate error handling and consider using established logging frameworks like NLog or log4net for more advanced logging needs in production applications.

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Logging in Visual Basic .NET