log4net argument to LogManager.GetLogger

Question

Why do most log4net examples get the logger for a class by doing this:

private static ILog logger = 
    LogManager.GetLogger(
    System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

Rather than just passing typeof(MyClass):

private static ILog logger = LogManager.GetLogger(typeof(MyClass));

Is there any other reason for doing this, beside the fact that the first option does not require you to type a specific class name?

Answer 1

I think you've got the reason. I do it that way so I don't have to worry about the class name and can just copy and paste boiler plate code in a new class.

For the official answer, see: How do I get the fully-qualified name of a class in a static block? at the log4net faq

Answer 2

I'm an NLog user, and usually this boils down to :

var _logger = LogManager.GetCurrentClassLogger();

It seemed a bit strange that you need to go through reflection in Log4Net, so I had a look in the NLog source code, and lo and behold, this is what they do for you:

[MethodImpl(MethodImplOptions.NoInlining)]
public static Logger GetCurrentClassLogger()
{
    string loggerName;
    Type declaringType;
    int framesToSkip = 1;
    do
    {
#if SILVERLIGHT
        StackFrame frame = new StackTrace().GetFrame(framesToSkip);
#else
        StackFrame frame = new StackFrame(framesToSkip, false);
#endif
        var method = frame.GetMethod();
        declaringType = method.DeclaringType;
        if (declaringType == null)
        {
            loggerName = method.Name;
            break;
        }
        framesToSkip++;
        loggerName = declaringType.FullName;
    } while (declaringType.Module.Name.Equals("mscorlib.dll", StringComparison.OrdinalIgnoreCase));
    return globalFactory.GetLogger(loggerName);
}

I guess I would write something similar for Log4Net as an extension or static method instead of pasting the reflection as part of my boiler code :)

Answer 3

As you say - its convenient as you can create a logger in a method without knowing the name of the class (trivial I know) but allows you to cut and paste methods between classes without having to rename the call.

Answer 4

I think the reason is, that you get the type of the runtime type using the .DeclaringType() method. You can use the logger in a base class and still see the actual type of your object in the loggers output. That makes investigations much more convinient.