How to refactor log4net statements in c#?

Question

Ok so after reading danben's answer on this post, I guess I'm convinced of the need for writting this kind of code, atleast in a lot of cases. My managers seem to be agreeing too.

if (log.IsDebugEnabled)
     log.Debug("ZDRCreatorConfig("+rootelem.ToString()+")");
if (log.IsInfoEnabled)
     log.Info("Reading Configuration . . .");

The problem with it is it bugs the heck out of me seeing all these if statements placed everywhere just to do a simple log statement.

My question is, how might we refactor this into a class without reproduceing the performance problem of having to evaluate the arguments to the log method?

Simply putting it in a class as a static method doesn't help, because when you pass the Object message it still has to evaluate the argument:

public class LogHelper {
     public static Info(ILog log, Object message) {
          if(log.IsInfoEnabled) { log.Info(message); }
     }
}

C# apparently doesn't support forcing a method to be inline, so that solution isn't available. MACROs are not supported in C#. What can we do?!?!

UPDATE: Thanks for the replies, I have not forgot about this one; it's just low priorty on my list right now. I will get to it and award the answer once I get caught up a bit. Thanks.

Another UPDATE:
well ... I still haven't look at this closly yet, and both of you deserve the correct answer; but I awarded Tanzelax the answer because I agree, I think they will be automatically inlined. The link he posted does good job of convincing me I shouldn't worry too much about this right now, which is also good lol. I'll still look at those lambda things later. Thanks for the help!

Answer 1

One simple solution is to use lambda expressions to effectively defer the message generation until it's needed, if it's needed:

public static class LogHelper {
    public static void Info(this ILog log, Func<Object> messageProvider) {
        if(log.IsInfoEnabled) { log.Info(messageProvider()); }
    }
}

Call it with:

log.Info(() => "This is expensive: " + CalculateExpensiveValue());