C#
Log providers
Learn Console and Debug log providers.
Log providers
A provider decides where logs go. Two common providers: ConsoleLoggerProvider writes to the console; DebugLoggerProvider writes to Visual Studio's Output window. Multiple providers can be attached to the same logger.
Providers are configured through a factory: loggerFactory.AddConsole().AddDebug(). So a single ILogger<T> call lands in both the console and the debugger. In production Debug is turned off; only Console or a file remains.
Multiple providers
A logger can write to several providers at once. For example Console and Debug both receive the same message; the user sees it on the console, the developer in the Output window. This is one call, many targets.
In tests this multi-target shape is easy to verify with a fake provider: a provider that collects logs in memory; then you check its contents with Assert.Equal. This is more reliable than capturing real console output.
Exercise Implement Console and Debug providers
Define an ILogger<T> interface with void LogInformation(string message). ConsoleLogger<T> calls Console.WriteLine("[INF] " + message). DebugLogger<T> calls System.Diagnostics.Debug.WriteLine. In Main, create one of each logger and call LogInformation; send "Konsola yazıldı" to Console and "Hata ayıklayıcıya yazıldı" to Debug.
Show example solution
Define interface ILogger<T> { void LogInformation(string message); }. Write class ConsoleLogger<T> : ILogger<T> { public void LogInformation(string message) => Console.WriteLine("[INF] " + message); }. Write class DebugLogger<T> : ILogger<T> { public void LogInformation(string message) => Debug.WriteLine("[INF] " + message); }. In Main: var c = new ConsoleLogger<Program>(); c.LogInformation("Konsola yazıldı"); var d = new DebugLogger<Program>(); d.LogInformation("Hata ayıklayıcıya yazıldı");
Example solution:
using System;
using System.Diagnostics;
public interface ILogger<T>
{
void LogInformation(string message);
}
public class ConsoleLogger<T> : ILogger<T>
{
public void LogInformation(string message) =>
Console.WriteLine("[INF] " + message);
}
public class DebugLogger<T> : ILogger<T>
{
public void LogInformation(string message) =>
Debug.WriteLine("[INF] " + message);
}
class Program
{
static void Main()
{
var console = new ConsoleLogger<Program>();
console.LogInformation("Konsola yazıldı");
var debug = new DebugLogger<Program>();
debug.LogInformation("Hata ayıklayıcıya yazıldı");
}
}
Test yourself
-
Which provider writes to the Visual Studio Output window?
- DebugLoggerProvider
- ConsoleLoggerProvider
- FileLoggerProvider
- EventLogLoggerProvider
Show answer
DebugLoggerProvider — Correct. DebugLoggerProvider writes to the debugger via System.Diagnostics.Debug.
-
Match providers to their target
- ConsoleLoggerProvider
- Console window
- DebugLoggerProvider
- Debugger output
- AddConsole
- Adds the console provider
- AddDebug
- Adds the debug provider
-
Complete the provider-add call
loggerFactory.Add____();
Show answer
loggerFactory.AddConsole();
Next lesson: Summary - Logging
