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From Leo Simons <leosim...@apache.org>
Subject Re: cvs commit: avalon/src/java/org/apache/avalon/framework/logger CommonsLogger.java
Date Sat, 08 Feb 2003 19:48:05 GMT
Paul Hammant wrote:
> Leo,
>>  public final class CommonsLogger
>>      implements Logger, Log
> I'm not sure this adds anything to A-F.

I thought about this for a long time before doing anything, and I'm 
relatively sure that it does now :D. There's a lot of people using 
commons-logging, and quite a few people have requested or suggested that 
avalon use or at least enable the use of commons-logging. So it 
satisfies a real, existing requirement.

Adding this single class doesn't have any impact on existing avalon code 
(or future avalon code) and is fully backwards-compatible. It adds only 
minimally to the size of avalon-framework.jar. Maintainance overhead is 
also neglegible. It enables future integration of alternative 
commons-logging-based logging solutions.

Besides the technical equation, I must admit I have also given thought 
to the positive vibes something like this can generate. It shows there 
really is no reason to be sceptical about the healthy relationship 
between the various projects.

> We already had a means of 
> delegation to Commons-Logging.

we do? Where?

> Be careful dude as the static and instance worlds of logging are 
> idealogically opposed.

I wouldn't go that far, but yep, there's definately room for problems 
when we mix the two. However, I believe there can be valid reasons to 
indeed want to mix the "pure" IoC/COP avalon promotes and the very 
commonly used static factory pattern together.

For example, consider an application with lots of tight coupling to the 
commons-logging library. If you want to wrap some of its classes to be 
avalon components, your life will be much easier if you can do something 

class WorkerWrapper extends AbstractLogEnabled {
     initialize() throws Exception
         if( ! m_logger instanceof CommonsLogger )
             throw new IllegalStateException(
                 "doing lazy migration...CommonsLogger required!" );

         m_worker = new Worker(); // like commons-digester :D
         m_worker.setLogger( (CommonsLogger)m_logger );

It might be a little 'ugly', but it sure would make using avalon a 
little easier in these situations.

Do you think adding in this class can/will lead to actual problems, 
besides sacrificing a little "purity"? If so, where, and how?


- Leo

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