[Commons Wiki] Update of "Logging/StaticLog" by SimonKitching

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The following page has been changed by SimonKitching:
http://wiki.apache.org/jakarta-commons/Logging/StaticLog

The comment on the change is:
Add info about fixing existing code

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  actually turns up logging to debug on ''all'' applications, though output from applications other than
  the one of interest is then suppressed again before being output.
  
+ == Fixing Existing Library Code ==
+ 
+ If you already have some library-type code that uses static log objects, and want to fix it after reading
+ this page, be careful of one issue: changing a static member to a non-static one changes the
+ serialization format of the class. The serialVersionUID of the class must change, and
+ as a result serialized versions of the old class will not load.
+ 
+ A possible (untested) alternative is to add a method like this:
+ {{{
+   private transient Log log;
+   private Log getLog() {
+     if (log == null)
+       log=LogFactory.getLog(Some.class);
+     return log;
+   }
+ 
+   // old code
+   // log.debug("foo");
+ 
+   // new code
+   getLog().debug("foo");
+ }}}
+ 
+ Like static members, transient ones are not part of the serialized data so this should be
+ a serialization-compatible change.
+ 

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