Any reason why log field should private static?

here is in C#:

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

Not only 开发者_运维百科in C# but another language i saw the same.. any thought?

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It's private because other classes should not access MyClass' log.

It's static because it doesn't depend on the class instance. (And so that it can be used by static methods)

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So that the field isn't inherited by your sub-classes.

Take this example:

class BaseFoobar
{
   public static readonly ILog log = LogManager.GetLogger(typeof(BaseFoobar));
}

class SpecializedFoobar : BaseFoobar
{
   public void Whatever()
   {
      log.Error("I exploded");
   }
}

If SpecializedFoobar's Whatever() function is ever called the co-responding log would be invalid:

[MyApp.BaseFoobar]: ERROR: I exploded