Question

In my C# project, I use log4net for debugging. But for the Release build, I need to remove any dependency to log4net. I’m not sure what is the right way to go about it.

Having #if DEBUG … endif through the code is very messy, and I have to manually add/remove the Reference to log4net when I compile in Debug or Release mode.

The other option I thought about it is to somehow switch the “real” lotg4net with a mock class in the Release build, but I’m not sure how to do this.

What is the best way to remove a dependency, log4net in my case, in the Release build?

Answer 1

Along the lines of M.Babcock’s answer: you are after dependency inversion. You do not necessarily have to use a dependency injection container but you will need to abstract your logging.

Something like this:

public interface ILog
{
    void Trace(string message);
    void Debug(string message);
    void Error(string message);
    // and whatever you need
}

Then you have different implementations:

public class NullLog : ILog { ... } // does nothing --- all calls are empty
public class Log4NetLog : ILog { ... } // initializes Log4Net and does logging

You could then use a static class as the main entry point:

public static class Log
{
    private ILog log = new NullLogger();

    public static void Assign(ILog log)
    {
        this.log = log;
    }

    public static void Debug(string message)
    {
        log.Debug(message);
    }

    // ...and other implementations...
}

Now you need to wire this up in your startup code. Here you can use a container or use conditional compilation:

#if DEBUG
    Log.Assign(new Log4NetLogger);
#endif

These are the broad strokes. I have some logging infrastructure code as part of my service bus: http://shuttle.codeplex.com/

ILog:
http://shuttle.codeplex.com/SourceControl/changeset/view/c49f328edd17#Shuttle.Core%2fsource%2fShuttle.Core.Infrastructure%2fLogging%2fILog.cs

NullLog:
http://shuttle.codeplex.com/SourceControl/changeset/view/c49f328edd17#Shuttle.Core%2fsource%2fShuttle.Core.Infrastructure%2fLogging%2fNullLog.cs

Log4NetLog:
http://shuttle.codeplex.com/SourceControl/changeset/view/c49f328edd17#Shuttle.Core%2fsource%2fShuttle.Core.Infrastructure.Log4Net%2fLog4NetLog.cs

Hope that helps.