Stan, This is exactly the way we handle logging. In fact, our developer's code knows nothing about log4j -- it is all wrapped within some custom classes -- so that we could at some future date swap out log4j and replace it with something else. We haven't run into any problems with regard to the missing classes you refer to.
Kevin -----Original Message----- From: Silvert, Stan [mailto:[EMAIL PROTECTED]] Sent: Monday, January 14, 2002 12:40 To: [EMAIL PROTECTED] Subject: Clever Logging? I am responsible for defining standards around how our developers use Log4J. When our company started using Log4J a couple of months ago, I told developers to use this technique in their code: public class MyClass { private static final Category LOG = Category.getInstance(MyClass.class.getName()); private static boolean DEBUG() { return LOG.isDebugEnabled(); } } So, for all debug statements, write something like this: if (DEBUG()) LOG.debug("The value of my vars are: " + v1 + " and " + v2); If not a debug statement, just do something like this: LOG.info("My info message"); That all worked fine, except that developers would make the mistake of putting the wrong class name inside the getInstance() method. This would usually happen when they would cut and paste code. So, one of our developers came up with a clever solution to cut down on the mistakes. He created a logging utility that could automatically read the stack frames, discover which class logged the message, and invoke logging from the proper Category. Here is how he did it: public class LogUtil { /** * Extends <code>java.lang.SecurityManager</code> to provide the <code>getClassName()</code> * method. */ private static class ClassGetter extends SecurityManager { // Inner class necessary because getClassContext() is protected /** * Returns the name of the calling class. * @return the name of the calling class */ public String getClassName() { // getClassContext() returns the current execution stack trace // as an array of classes -- the element at index 0 is the class // of the currently executing method, the element at index 1 is // the class of that method's caller, and so on. So, 0 is going // to be this class (ClassGetter), 1 will be LogUtil, and 2 will // be the magic number we are after. return getClassContext()[2].getName(); } } private static ClassGetter classGetter = new ClassGetter(); /** * Returns the name of the calling class. * Intended to be used from static methods or initializers to automagically * determine the calling class's name. * @return the name of the calling class */ public static String getClassName() { return classGetter.getClassName(); } /////////////////////////////////////////////////////////////////// /** * Returns <code>true</code> if debugging is enabled for a given category * * @return <code>true</code> if debugging is enabled, * <code>false</code> if not */ public static boolean DEBUG() { Category cat = Category.getInstance(classGetter.getClassName()); return cat.isDebugEnabled(); } /////////////////////////////////////////////////////////////////// /** * Logs the given message with <code>DEBUG</code> priority, to the category * automagically derived from the calling class name. * * @param msg the message to log */ public static void debug(String msg) { Category cat = Category.getInstance(classGetter.getClassName()); cat.debug(msg); } } This looks very nice and seems to solve all the problems quite well - except for one thing. I have been reading about how some JIT's can remove stack frames during optimization. This would cause messages to once again be logged under the wrong Category. My questions to the folks on this list are, What is your opinion of both techniques? Do you know other developers who have tried the "clever" approach and run into the "disappearing stack frame" problem? Is there another solution we are overlooking? (short of disabling cut and paste from everyone's IDE) Thanks in advance for your input. Stan Silvert -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]> -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>